MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Ultramicroscopy' source. Tue, 07 Feb 2012 06:39:44 +0100 http://www.medworm.com/index.php?rid=5513374&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22094413%26dopt%3DAbstract Authors: Xie KY, Breen AJ, Yao L, Moody MP, Gault B, Cairney JM, Ringer SP Abstract Nitrided steels are widely used in the engineering field due to their superior hardness and other attractive properties. Atom probe tomography (APT) was employed to study two Nb-microalloyed CASTRIP steels with different N contents. A major challenge of using APT to study this group of materials is the presence of tails after Fe peaks in the mass spectra, which overestimates the composition for alloying elements such as Nb and Cu in the steels. One important factor that contributes to the tails is believed to be delayed field evaporation from Fe(2+). This artefact of the mass spectrum was observed to be the most severe when voltage pulsing was used. The application of laser pulses with energy rangin... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5513374 Sat, 17 Dec 2011 20:48:43 +0100 5513374 http://www.medworm.com/index.php?rid=5513373&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22094414%26dopt%3DAbstract Authors: Lu J, Gao SP, Yuan J Abstract Electron energy-loss near-edge fine structures (ELNES) were calculated for graphene, doped graphene, a hexagonal BN monolayer, and a hexagonal BC(2)N layer using an ab initio pseudopotential plane wave method including the core-hole effect. Spectral features that can be used to distinguish different chemical environments are identified. The spectral features are closely related to the atomic species and arrangement. The connection between chemical environments and fine structures is discussed. PMID: 22094414 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5513373 Sat, 17 Dec 2011 20:48:32 +0100 5513373 http://www.medworm.com/index.php?rid=5513372&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22104023%26dopt%3DAbstract Multislice frozen phonon high angle annular dark-field image simulation study of Mo-V-Nb-Te-O complex oxidation catalyst "M1". Ultramicroscopy. 2012 Jan;112(1):69-75 Authors: Blom DA Abstract Multislice frozen phonon calculations were performed on a model structure of a complex oxide which has potential use as an ammoxidation catalyst. The structure has 11 cation sites in the framework, several of which exhibit mixed Mo/V substitution. In this paper the sensitivity of high-angle annular dark-field (HAADF) imaging to partial substitution of V for Mo in this structure is reported. While the relationship between the average V content in an atom column and the HAADF image intensity is not independent of thickness, it is a fairly weak function of thickness suggesting that HAADF ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5513372 Sat, 17 Dec 2011 20:48:22 +0100 5513372 http://www.medworm.com/index.php?rid=5513377&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22094372%26dopt%3DAbstract Authors: Te Riet J, Katan AJ, Rankl C, Stahl SW, van Buul AM, Phang IY, Gomez-Casado A, Schön P, Gerritsen JW, Cambi A, Rowan AE, Vancso GJ, Jonkheijm P, Huskens J, Oosterkamp TH, Gaub H, Hinterdorfer P, Figdor CG, Speller S Abstract Single-molecule force spectroscopy studies performed by Atomic Force Microscopes (AFMs) strongly rely on accurately determined cantilever spring constants. Hence, to calibrate cantilevers, a reliable calibration protocol is essential. Although the thermal noise method and the direct Sader method are frequently used for cantilever calibration, there is no consensus on the optimal calibration of soft and V-shaped cantilevers, especially those used in force spectroscopy. Therefore, in this study we aimed at establishing a commonly accepted approach to ac... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5513377 Thu, 01 Dec 2011 05:00:00 +0100 5513377 http://www.medworm.com/index.php?rid=5513376&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22094373%26dopt%3DAbstract Authors: Potapov P, Engelmann HJ Abstract We introduce a method to characterize the chemical distribution in nanostructures using STEM and affiliated spectroscopy techniques. The method is applicable to any nanostructure where the continuous layers of arbitrary geometry and dimensions can be identified. The key feature of the suggested approach is digital warping of the original STEM image into the quasi-1D image. The chemical profiles of high resolution and high signal-to-noise ratio can be extracted from the minimal set of the STEM spectroscopy data while minimizing material damage during acquisitions. Finally, the 2D chemical maps of the area of interest are reconstructed. PMID: 22094373 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5513376 Thu, 01 Dec 2011 05:00:00 +0100 5513376 http://www.medworm.com/index.php?rid=5513375&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22094374%26dopt%3DAbstract We present a fast and versatile algorithm for the reconstruction of the grain structure from 2d and 3d Electron Back Scatter Diffraction (EBSD) data. The algorithm is rigorously derived from the modeling assumption that grain boundaries are located at the bisectors of adjacent measurement locations. This modeling assumption immediately implies that grains are composed of Voronoi cells corresponding to the measurement locations. Thus our algorithm is based on the Voronoi decomposition of the 2d or 3d measurement domain. It applies to any geometrical configuration of measurement locations and allows for missing data due to measurement errors. The definition of grains as compositions of Voronoi cells implies another fundamental feature of the proposed algorithm-its invariance with respect to ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5513375 Thu, 01 Dec 2011 05:00:00 +0100 5513375 http://www.medworm.com/index.php?rid=5420147&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088506%26dopt%3DAbstract Authors: Lee Z, Meyer JC, Rose H, Kaiser U Abstract The dependence of high-resolution transmission electron microscopy (HRTEM) image contrast of graphene on the adjustable parameters of an aberration-corrected microscope operated at 80 and 20kV has been calculated and, for 80kV, compared with measurements. We used density functional theory to determine the projected atom potential and obtained the image intensity by averaging over the energy distribution of the imaging electrons, as derived from the electron energy loss spectroscopy measurements. Optimum image contrast has been determined as a function of energy spread of the imaging electrons and chromatic aberration coefficient, showing that significant improvement of contrast can be achieved at 80kV with the help of a monochroma... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420147 Sun, 30 Oct 2011 04:00:00 +0100 5420147 http://www.medworm.com/index.php?rid=5420146&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088507%26dopt%3DAbstract Authors: Yokosawa T, Alan T, Pandraud G, Dam B, Zandbergen H Abstract We have developed a nanoreactor, sample holder and gas system for in-situ transmission electron microscopy (TEM) of hydrogen storage materials up to at least 4.5bar. The MEMS-based nanoreactor has a microheater, two electron-transparent windows and a gas inlet and outlet. The holder contains various O-rings to have leak-tight connections with the nanoreactor. The system was tested with the (de)hydrogenation of Pd at pressures up to 4.5bar. The Pd film consisted of islands being 15nm thick and 50-500nm wide. In electron diffraction mode we observed reproducibly a crystal lattice expansion and shrinkage owing to hydrogenation and dehydrogenation, respectively. In selected-area electron diffraction and bright/dark-f... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420146 Fri, 28 Oct 2011 04:00:00 +0100 5420146 http://www.medworm.com/index.php?rid=5420156&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079496%26dopt%3DAbstract Authors: Niewieczerzał D, Oleksy C, Szczepkowicz A Abstract Multi-scale simulations of field ion microscopy images of faceted and hemispherical samples are performed using a 3D model. It is shown that faceted crystals have compressed images even in cases with no shank. The presence of the shank increases the compression of images of faceted crystals quantitatively in the same way as for hemispherical samples. It is hereby proven that the shank does not influence significantly the local, relative variations of the magnification caused by the atomic-scale structure of the sample. PMID: 22079496 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420156 Tue, 25 Oct 2011 04:00:00 +0100 5420156 http://www.medworm.com/index.php?rid=5420145&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088508%26dopt%3DAbstract Authors: Mitsuishi K, Hashimoto A, Takeguchi M, Shimojo M, Ishizuka K Abstract The imaging properties of bright field and annular dark field scanning confocal electron microscopy (BF-SCEM and ADF-SCEM) are discussed based on their point spread functions (PSFs) in comparison with multislice simulations. Although the PSFs of BF-SCEM and ADF-SCEM show similar hourglass shapes, their numerical distributions are quite different: BF-SCEM PSF is always positive and shows a center of symmetry whereas the ADF-SCEM PSF is complex and has Hermitian symmetry. These PSF properties explain the large elongation effect in BF-SCEM for laterally extended object and almost no-elongation in ADF-SCEM, illustrating the importance of the numerical analysis of PSFs. The Hermitian symmetry of the ADF-SCEM ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420145 Tue, 25 Oct 2011 04:00:00 +0100 5420145 http://www.medworm.com/index.php?rid=5420154&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22081044%26dopt%3DAbstract In this study, the thickness dependence of the minimum contrast focus has been investigated by dynamical image simulations for amorphous model structures of carbon, germanium, and tungsten, which were constructed by molecular dynamics simulations. The calculation results show that the minimum contrast focus varies with the object thickness, supporting the use of an effective object plane close to the midplane instead of the exit plane of a sample, as suggested by Bonhomme and Beorchia [J. Phys. D: Appl. Phys. 16, 705 (1983)] and Lentzen [Microscopy and Microanalysis 12, 191 (2006)]. Thus supported particles and wedge-shaped crystals with symmetrical top and bottom surfaces could be imaged at a focus condition independent of the uneven bottom face. Image simulations of crystalline samples a... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420154 Fri, 21 Oct 2011 04:00:00 +0100 5420154 http://www.medworm.com/index.php?rid=5420158&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079380%26dopt%3DAbstract Authors: Wan C, Vaughn JM, Sadowski JT, Kordesch ME Abstract Thermionic electron emission from 200 to 500nm thick coatings of scandium oxide on tungsten foil have been examined in thermionic emission microscopy, spectroscopic photoelectron microcopy, synchrotron radiation and ultraviolet photoelectron spectroscopy (UPS). A clear dependence of the scandium oxide-W electron yield on the grain orientation of the polycrystalline tungsten is observed in thermionic emission and photoelectron emission. PMID: 22079380 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420158 Mon, 17 Oct 2011 04:00:00 +0100 5420158 http://www.medworm.com/index.php?rid=5420157&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079381%26dopt%3DAbstract Authors: Orloff J Abstract High resolution focused ion beam (FIB) technology depends on electrostatic optics. As a longtime researcher on electrostatic optics Dr. Gertrude Rempfer has had a great impact not only on the development of FIB technology but, as a result, also on several technology areas dependent on it. This paper provides a brief description of how that came about. PMID: 22079381 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420157 Thu, 13 Oct 2011 04:00:00 +0100 5420157 http://www.medworm.com/index.php?rid=5420152&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088443%26dopt%3DAbstract Authors: Buijsse B, van Laarhoven FM, Schmid AK, Cambie R, Cabrini S, Jin J, Glaeser RM Abstract A novel design is described for an aperture that blocks a half-plane of the electron diffraction pattern out to a desired scattering angle, and then - except for a narrow support beam - transmits all of the scattered electrons beyond that angle. Our proposed tulip-shaped design is thus a hybrid between the single-sideband (ssb) aperture, which blocks a full half-plane of the diffraction pattern, and the conventional (i.e. fully open) double-sideband (dsb) aperture. The benefits of this hybrid design include the fact that such an aperture allows one to obtain high-contrast images of weak-phase objects with the objective lens set to Scherzer defocus. We further demonstrate that such apert... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420152 Tue, 04 Oct 2011 04:00:00 +0100 5420152 http://www.medworm.com/index.php?rid=5420159&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079353%26dopt%3DAbstract Authors: Kim YC, Ahn SJ, Oh TS, Kim DW, Kim HS, Jang WK Abstract Since the development of microcolumn system, it attracted much attention because multiple microcolumns can be assembled into arrayed form, which is expected to generate multiple electron beams and overcome the disadvantage of electron beam inspection equipments, low throughput [1-3]. However, it is not easy to apply a microcolumn to the practical inspection or testing equipment since its scanning area is too small. Even if the arrayed operation using multiple microcolumns can overcome this limit, it requires complicated supporting systems and related technologies to operate a number of microcolumns simultaneously. Therefore, we tried to modify microcolumn design itself so that it can have a large field of view. In thi... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420159 Sat, 01 Oct 2011 04:00:00 +0100 5420159 http://www.medworm.com/index.php?rid=5420153&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088442%26dopt%3DAbstract Authors: Forbes BD, D'Alfonso AJ, Findlay SD, Van Dyck D, Lebeau JM, Stemmer S, Allen LJ Abstract In conventional transmission electron microscopy, thermal scattering significantly affects the image contrast. It has been suggested that not accounting for this correctly is the main cause of the Stobbs factor, the ubiquitous, large contrast mismatch found between theory and experiment. In the case where a hard aperture is applied, we show that previous conclusions drawn from work using bright field scanning transmission electron microscopy and invoking the principle of reciprocity are reliable in the presence of thermal scattering. In the aperture-free case it has been suggested that even the most sophisticated mathematical models for thermal diffuse scattering lack in their numerica... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420153 Sat, 01 Oct 2011 04:00:00 +0100 5420153 http://www.medworm.com/index.php?rid=5420148&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088505%26dopt%3DAbstract Authors: Cummings ML, Chien TY, Preissner C, Madhavan V, Diesing D, Bode M, Freeland JW, Rose V Abstract The combination of high-brilliance synchrotron radiation with scanning tunneling microscopy opens the path to high-resolution imaging with chemical, electronic, and magnetic contrast. Here, the design and experimental results of an in-situ synchrotron enhanced x-ray scanning tunneling microscope (SXSTM) system are presented. The system is designed to allow monochromatic synchrotron radiation to enter the chamber, illuminating the sample with x-ray radiation, while an insulator-coated tip (metallic tip apex open for tunneling, electron collection) is scanned over the surface. A unique feature of the SXSTM is the STM mount assembly, designed with a two free-flex pivot, providing a... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420148 Sat, 01 Oct 2011 04:00:00 +0100 5420148 http://www.medworm.com/index.php?rid=5420155&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22079497%26dopt%3DAbstract Authors: Wu CH, Reynolds WT, Murayama M Abstract A software package "SADP Tools" is developed as a complementary diffraction pattern analysis tool. The core program, called AutoSADP, is designed to facilitate automated measurements of d-spacing and interplaner angles from TEM selected area diffraction patterns (SADPs) of single crystals. The software uses iterative cross correlations to locate the forward scattered beam position and to find the coordinates of the diffraction spots. The newly developed algorithm is suitable for fully automated analysis and it works well with asymmetric diffraction patterns, off-zone axis patterns, patterns with streaks, and noisy patterns such as Fast Fourier transforms of high-resolution images. The AutoSADP tool runs as a macro for the Digital Mic... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420155 Thu, 29 Sep 2011 04:00:00 +0100 5420155 http://www.medworm.com/index.php?rid=5420160&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22078715%26dopt%3DAbstract Authors: Kirkland A, Midgley P PMID: 22078715 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420160 Thu, 22 Sep 2011 04:00:00 +0100 5420160 http://www.medworm.com/index.php?rid=5420151&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088444%26dopt%3DAbstract We report the implementation of an electrostatic Einzel lens (Boersch) phase plate in a prototype transmission electron microscope dedicated to aberration-corrected cryo-EM. The combination of phase plate, C(s) corrector and Diffraction Magnification Unit (DMU) as a new electron-optical element ensures minimal information loss due to obstruction by the phase plate and enables in-focus phase contrast imaging of large macromolecular assemblies. As no defocussing is necessary and the spherical aberration is corrected, maximal, non-oscillating phase contrast transfer can be achieved up to the information limit of the instrument. A microchip produced by a scalable micro-fabrication process has 10 phase plates, which are positioned in a conjugate, magnified diffraction plane generated by the DMU... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420151 Sat, 17 Sep 2011 04:00:00 +0100 5420151 http://www.medworm.com/index.php?rid=5420150&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088445%26dopt%3DAbstract Authors: Mayer M, Grévent C, Szeghalmi A, Knez M, Weigand M, Rehbein S, Schneider G, Baretzky B, Schütz G Abstract Best resolutions in X-ray focusing are obtained to date by using diffractive lenses called Fresnel zone plates (FZPs). Their further improvement is nevertheless hindered by fundamental limitations in the employed manufacturing techniques. Here, we show a novel method to fabricate FZPs based on multilayer deposition with atomic layer deposition (ALD) and subsequent sectioning with focused ion beam (FIB). For the first time a multilayer FZP working in the soft X-ray range was prepared and could achieve the best resolution obtained so far for multilayer FZPs by resolving features below 39nm in size in a scanning soft X-ray microscope. The new technique presents high pot... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420150 Sat, 17 Sep 2011 04:00:00 +0100 5420150 http://www.medworm.com/index.php?rid=5420149&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22088446%26dopt%3DAbstract Authors: Wisniewski W, Völksch G, Rüssel C Abstract Surface crystallized samples of glass-ceramics containing cordierite, rhombohedral BaAl(2)B(2)O(7) and fresnoite were analyzed using electron backscatter diffraction (EBSD). The first two materials were chosen because surface crystallized samples of these materials have previously been shown to contain crystals covered by a very thin layer of glass. In all materials, EBSD pattern degradation occurs if the step size of a scan is chosen to be small. It is shown that the minimum step size enabling an evaluable EBSD-scan increases notably, if the crystals are covered by a thin layer of glass. It is also shown that pattern degradation may be utilized to prove the existence of such a thin glass or otherwise thermally sensitive layer. ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5420149 Sat, 17 Sep 2011 04:00:00 +0100 5420149 http://www.medworm.com/index.php?rid=5297134&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963779%26dopt%3DAbstract Authors: Oh YJ, Huber HP, Hochleitner M, Duman M, Bozna B, Kastner M, Kienberger F, Hinterdorfer P Abstract Microwave measurements combined with scanning probe microscopy is a novel tool to explore high-localized mechanical and electrical properties of biological species. Complex permittivities and permeabilities are detected through slight variations of an incident microwave signal. Here we report the high-frequency dependence of the electromagnetic dynamic characteristics in human monocytic leukemia cells (THP1) through local measurements by scanning microwave microscopy (SMM). The amplitude and phase images were shown to depend on the applied resonance frequency. While the amplitude yields information about the resistivity determined by the water and the ionic strength, the phas... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5297134 Sat, 17 Sep 2011 04:00:00 +0100 5297134 http://www.medworm.com/index.php?rid=5297133&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21963780%26dopt%3DAbstract Authors: Hermann P, Hecker M, Chumakov D, Weisheit M, Rinderknecht J, Shelaev A, Dorozhkin P, Eng LM Abstract The spatial resolution and high sensitivity of tip-enhanced Raman spectroscopy allows the characterization of surface features on a nano-scale. This technique is used to visualize silicon-based structures, which are similar in width to the transistor channels in present leading-edge CMOS devices. The reduction of the intensive far-field background signal is crucial for detecting the weak near-field contributions and requires beside a careful alignment of laser polarization and tip axis also the consideration of the crystalline sample orientation. Despite the chemical identity of the investigated sample surface, the structures can be visualized by the shift of the Raman peak... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5297133 Fri, 16 Sep 2011 04:00:00 +0100 5297133 http://www.medworm.com/index.php?rid=5280130&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21945998%26dopt%3DAbstract Authors: Tejada A, den Dekker AJ, Van den Broek W Abstract Transmission electron microscopes (TEMs) are the tools of choice for academic and industrial research at the nano-scale. Due to their increasing use for routine, repetitive measurement tasks (e.g., quality control in production lines) there is a clear need for a new generation of high-throughput microscopes designed to autonomously extract information from specimens (e.g., particle size distribution, chemical composition, structural information, etc.). To aid in their development, a new engineering perspective on TEM design, based on principles from systems and control theory, is proposed here: measure-by-wire (not to be confused with remote microscopy). Under this perspective, the TEM operator yields the direct control of ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5280130 Thu, 08 Sep 2011 04:00:00 +0100 5280130 http://www.medworm.com/index.php?rid=5280129&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21946001%26dopt%3DAbstract Authors: Pantel R Abstract In this paper, during dopant analysis of silicon devices, we have observed a phenomenon generally neglected in EDX analysis: the coherent Bremsstrahlung (CB). We discussed the reason why and came to the conclusion that the analytical TEM used for these experiments presents a configuration and performances, which makes this equipment very sensitive to the CB effect. This is due to large collection solid angle and high counting rate of the four silicon drift EDX detectors (SDD), a high brightness electron source providing large probe current and moreover a geometry favorable to on axis crystal observations. We analyzed silicon devices containing Si [110] and Si [100] crystal areas at different energies (80-120-200keV). We also observed relaxed SiGe (27 and ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5280129 Thu, 08 Sep 2011 04:00:00 +0100 5280129 http://www.medworm.com/index.php?rid=5260011&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21939617%26dopt%3DAbstract Authors: Kirkland EJ Abstract New aberration correctors present new challenges in optimizing (minimizing) the probe size in the STEM (Scanning Transmission Electron Microscope). A small probe is important for high resolution imaging and analytical microscopy. Some effects of aperture size, corrector accuracy, and higher order aberrations on probe size and image artifacts are calculated. Accumulated small errors in the aberration corrector can produce a significant decrease in image contrast, which may be important in quantitative image comparisons of theory and experiment. It is important to match the objective aperture to the accuracy of the corrector instead of just the (third order) spherical aberration of the objective as in the commonly used Scherzer conditions. PMID: 2193... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260011 Thu, 08 Sep 2011 04:00:00 +0100 5260011 http://www.medworm.com/index.php?rid=5260008&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21939620%26dopt%3DAbstract Authors: Tejada A, den Dekker AJ Abstract Frank's observation that a TEM bright-field image acquired under non-stationary conditions can be modeled by the time integral of the standard TEM image model [J. Frank, Nachweis von objektbewegungen im lichtoptis- chen diffraktogramm von elektronenmikroskopischen auf- nahmen, Optik 30 (2) (1969) 171-180.] is re-derived here using counting statistics based on Poisson's binomial distribution. The approach yields a statistical image model that is suitable for image analysis and simulation. PMID: 21939620 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260008 Thu, 08 Sep 2011 04:00:00 +0100 5260008 http://www.medworm.com/index.php?rid=5260012&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21937011%26dopt%3DAbstract Authors: Lee HS, Findlay SD, Mizoguchi T, Ikuhara Y Abstract The analysis of grain boundary structure in high resolution electron microscopy is often hindered by contrast variation within the grain boundary region which is not explained by simple models of the grain boundary structure. Recent work suggests that structural disorder along the beam direction and the presence of vacancies contribute significantly to this effect. One might expect a significant reduction in contrast in a Z-contrast image of a grain boundary would imply that vacancies present must result from the absence of heavier elements. Using a [001](210) Σ5 grain boundary in SrTiO(3) as a test case and first principles structure relaxation to calculate stable defect structures, we show that the reduction in the int... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260012 Tue, 06 Sep 2011 04:00:00 +0100 5260012 http://www.medworm.com/index.php?rid=5260006&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21939622%26dopt%3DAbstract Authors: Giannuzzi LA, Utlaut M Abstract 30keV Ga(+) focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z(2), and shows a non-monotonic relationship between contrast and Z(2). The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion-solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z(2), following the periodic behavio... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260006 Mon, 05 Sep 2011 04:00:00 +0100 5260006 http://www.medworm.com/index.php?rid=5260009&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21939619%26dopt%3DAbstract Authors: Vicary JA, Ulcinas A, Hörber JK, Antognozzi M Abstract Atomic force microscopy (AFM) has been very successful in measuring forces perpendicular to the sample plane. Here, we present the advantages of turning the AFM cantilever 90° in order for it to be perpendicular to the sample. This rotation leads naturally to the detection of in-plane forces with some extra advantages with respect to the AFM orientation. In particular, the use of extremely small (1μm wide) and soft (k≅10(-5)N/m) micro-fabricated cantilevers is demonstrated by recording their thermal power spectral density in ambient conditions and in liquid. These measurements lead to the complete characterisation of the sensors in terms of their stiffness and resonant frequency. Future applications, which will be... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260009 Sat, 27 Aug 2011 04:00:00 +0100 5260009 http://www.medworm.com/index.php?rid=5260010&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21939618%26dopt%3DAbstract Authors: Ruben G, Bosman M, D'Alfonso AJ, Okunishi E, Kondo Y, Allen LJ Abstract We study atomic-resolution annular electron energy-loss spectroscopy (AEELS) in scanning transmission electron microscopy (STEM) imaging with experiments and numerical simulations. In this technique the central part of the bright field disk is blocked by a beam stop, forming an annular entry aperture to the spectrometer. The EELS signal thus arises only from electrons scattered inelastically to angles defined by the aperture. It will be shown that this method is more robust than conventional EELS imaging to variations in specimen thickness and can also provide higher spatial resolution. This raises the possibility of lattice resolution imaging of lighter elements or ionization edges previously consider... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260010 Fri, 26 Aug 2011 04:00:00 +0100 5260010 http://www.medworm.com/index.php?rid=5260007&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21939621%26dopt%3DAbstract Authors: Hugon O, Joud F, Lacot E, Jacquin O, Guillet de Chatellus H Abstract The application of the non-conventional imaging technique LOFI (laser optical feedback imaging) to coherent microscopy is presented. This simple and efficient technique using frequency-shifted optical feedback needs the sample to be scanned in order to obtain an image. The effects on magnitude and phase signals such as vignetting and field curvature occasioned by the scanning with galvanometric mirrors are discussed. A simple monitoring method based on phase images is proposed to find the optimal position of the scanner. Finally, some experimental results illustrating this technique are presented. PMID: 21939621 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260007 Mon, 22 Aug 2011 04:00:00 +0100 5260007 http://www.medworm.com/index.php?rid=5260021&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930016%26dopt%3DAbstract We present an experimental proof of concept by recovering the exit-surface wave of a microfiber illuminated by a plane wave formed using a HeNe laser. PMID: 21930016 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260021 Mon, 01 Aug 2011 04:00:00 +0100 5260021 http://www.medworm.com/index.php?rid=5260020&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930017%26dopt%3DAbstract Authors: Schattschneider P, Verbeeck J Abstract The recent creation of electron vortex beams and their first practical application motivates a better understanding of their properties. Here, we develop the theory of free electron vortices with quantized angular momentum, based on solutions of the Schrödinger equation for cylindrical boundary conditions. The principle of transformation of a plane wave into vortices with quantized angular momentum, their paraxial propagation through round magnetic lenses, and the effect of partial coherence are discussed. PMID: 21930017 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260020 Mon, 01 Aug 2011 04:00:00 +0100 5260020 http://www.medworm.com/index.php?rid=5260019&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930018%26dopt%3DAbstract Authors: Esteban R, Vogelgesang R, Kern K Abstract We analyze simulations of the image generation process in apertureless Scanning Near-Field Optical Microscopy to study the differences between heterodyne interferometric and non-interferometric detection schemes implemented in experiments. Beyond the well-known possibilities of interferometry to enhance signals and extract optical phase information, we find that heterodyne interferometric detection may in fact lead to more robust and easier to interpret experimental results. Further, our results illustrate how simulations that do not include the use of interferometric detection in a given experiment can lead to significant disagreements with the measurements. PMID: 21930018 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260019 Mon, 01 Aug 2011 04:00:00 +0100 5260019 http://www.medworm.com/index.php?rid=5260018&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930019%26dopt%3DAbstract Authors: De Backer A, Van Aert S, Van Dyck D Abstract In this paper, it has been investigated how to measure atom column positions as accurately and precisely as possible using a focal series of images. In theory, it is expected that the precision would considerably improve using a maximum likelihood estimator based on the full series of focal images. As such, the theoretical lower bound on the variances of the unknown atom column positions can be attained. However, this approach is numerically demanding. Therefore, maximum likelihood estimation has been compared with the results obtained by fitting a model to a reconstructed exit wave rather than to the full series of focal images. Hence, a real space model-based exit wave reconstruction technique based on the channelling theory i... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260018 Mon, 01 Aug 2011 04:00:00 +0100 5260018 http://www.medworm.com/index.php?rid=5260017&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930020%26dopt%3DAbstract Authors: Phillips PJ, Brandes MC, Mills MJ, De Graef M Abstract The application of scanning transmission electron microscopy (STEM) to crystalline defect analysis has been extended to dislocations. The present contribution highlights the use of STEM on two oppositely signed sets of near-screw dislocations in hcp α-Ti with 6wt% Al in solid solution. In addition to common systematic row diffraction conditions, other configurations such as zone axis and 3g imaging are explored, and appear to be very useful not only for defect analysis, but for general defect observation. It is demonstrated that conventional TEM rules for diffraction contrast such as g·b and g·R are applicable in STEM. Experimental and computational micrographs of dislocations imaged in the aforementioned modes are ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260017 Mon, 01 Aug 2011 04:00:00 +0100 5260017 http://www.medworm.com/index.php?rid=5260016&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930021%26dopt%3DAbstract In this study, a quantitative approach is proposed to understand the effect of the accelerating voltage and the probe current on the physical resolution of EBSD. The accelerating voltage was varied from 5 to 30kV and probe currents of 1, 10, and 40nA were selected. The lateral, longitudinal, and depth resolutions at 10kV and 1nA were 34.5, 44.7, and 46nm for copper, respectively. When the accelerating voltage was in the range of 5-20kV, the ratio of the longitudinal to the lateral resolution was below the theoretical ratio of 2.9. Considering the channeling effect, the best physical depth resolution of 38nm was achieved at 5kV and 10nA. The physical depth resolution in an EBSD measurement is much larger due to the channel effect than that obtained without considering this effect. PMID:... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260016 Mon, 01 Aug 2011 04:00:00 +0100 5260016 http://www.medworm.com/index.php?rid=5260015&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930022%26dopt%3DAbstract We present the optical properties-the object/image distance, z(0), and the coefficients of spherical and chromatic aberration, C(s) and C(c), of both mirror types from an analysis of electron trajectories in the mirror field. From this analysis, we demonstrate that while the properties of both designs are similar, the additional parameters in the triode mirror improve the range of aberration that can be corrected. The triode mirror is also able to provide a dynamic adjustment range of chromatic aberration for fixed spherical aberration and focal length, or any permutation of these three parameters. While the dynamic range depends on the values of aberration correction needed, a nominal 10% tuning range is possible for most configurations accompanied by less than 1% change in the other two ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260015 Mon, 01 Aug 2011 04:00:00 +0100 5260015 http://www.medworm.com/index.php?rid=5260014&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930023%26dopt%3DAbstract Authors: Rebled JM, Yedra L, Estradé S, Portillo J, Peiró F Abstract The successful combination of electron beam precession and bright field electron tomography for 3D reconstruction is reported. Beam precession is demonstrated to be a powerful technique to reduce the contrast artifacts due to diffraction and curvature in thin foils. Taking advantage of these benefits, Precession assisted electron tomography has been applied to reconstruct the morphology of Sn precipitates embedded in an Al matrix, from a tilt series acquired in a range from +49° to -61° at intervals of 2° and with a precession angle of 0.6° in bright field mode. The combination of electron tomography and beam precession in conventional TEM mode is proposed as an alternative procedure to obtain 3D reconstruct... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260014 Mon, 01 Aug 2011 04:00:00 +0100 5260014 http://www.medworm.com/index.php?rid=5260013&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21930024%26dopt%3DAbstract Authors: Houben L, Bar Sadan M Abstract High-resolution electron tomography from a tilt series of transmission electron microscopy images requires an accurate image alignment procedure in order to maximise the resolution of the tomogram. This is the case in particular for ultra-high resolution where even very small misalignments between individual images can dramatically reduce the fidelity of the resultant reconstruction. A tomographic-reconstruction based and marker-free method is proposed, which uses an iterative optimisation of the tomogram resolution. The method utilises a search algorithm that maximises the contrast in tomogram sub-volumes. Unlike conventional cross-correlation analysis it provides the required correlation over a large tilt angle separation and guarantees a c... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5260013 Mon, 01 Aug 2011 04:00:00 +0100 5260013 http://www.medworm.com/index.php?rid=5175942&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864764%26dopt%3DAbstract Authors: Jornsanoh P, Thollet G, Ferreira J, Masenelli-Varlot K, Gauthier C, Bogner A Abstract This paper presents the development and the application of a new electron tomography technique based on STEM (Scanning Transmission Electron Microscopy) configuration in ESEM (Environmental Scanning Electron Microscopy). This combination provides a new approach for the characterization of the 3D structure of materials, as it optimizes a compromise between the resolution level of a few tens of nm and the large tomogram size due to the high thickness of transparency. The method is well adapted for non-conductive samples, and exhibits good contrast even for materials with low atomic number. The paper describes the development of a dedicated stage for this new tomography technique. Taking adv... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175942 Thu, 30 Jun 2011 23:00:00 +0100 5175942 http://www.medworm.com/index.php?rid=5175941&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864765%26dopt%3DAbstract Authors: Jin-Phillipp NY, Koch CT, van Aken PA Abstract Core-loss EFTEM tomography provides three-dimensional structural and chemical information. Multiple inelastic scattering occurring in thick specimens as well as orientation-dependent diffraction contrast due to multiple elastic scattering, however, often limit its applications. After demonstrating the capability of core-loss EFTEM tomography to reconstruct just a few monolayers thin carbon layer covering a Fe catalyst particle we discuss its application to thicker samples. We propose an approximate multiple-scattering correction method based on the use of zero-loss images and apply it successfully to copper whiskers, providing a significant improvement of the reconstructed 3D elemental distribution. We conclude this paper by a... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175941 Thu, 30 Jun 2011 23:00:00 +0100 5175941 http://www.medworm.com/index.php?rid=5175940&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864766%26dopt%3DAbstract We present a comparison that can be used to select the best inelastic signal for tomography, depending on different parameters such as the beam stability and nature of the sample. The appropriate signal will obviously also depend on the exact information which is requested. PMID: 21864766 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175940 Thu, 30 Jun 2011 23:00:00 +0100 5175940 http://www.medworm.com/index.php?rid=5175939&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864767%26dopt%3DAbstract Authors: Benzerara K, Menguy N, Obst M, Stolarski J, Mazur M, Tylisczak T, Brown GE, Meibom A Abstract We have investigated the nanotexture and crystallographic orientation of aragonite in a coral skeleton using synchrotron-based scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM). Polarization-dependent STXM imaging at 40-nm spatial resolution was used to obtain an orientation map of the c-axis of aragonite on a focused ion beam milled ultrathin section of a Porites coral. This imaging showed that one of the basic units of coral skeletons, referred to as the center of calcification (COC), consists of a cluster of 100-nm aragonite globules crystallographically aligned over several micrometers with a fan-like distribution and with the properties ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175939 Thu, 30 Jun 2011 23:00:00 +0100 5175939 http://www.medworm.com/index.php?rid=5175938&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864768%26dopt%3DAbstract Authors: Ngo DT, McVitie S Abstract We illustrate an approach which allows determining the out-of-plane component of the vortex core (polarity) in NiFe nanodots using Fresnel imaging in Lorentz electron microscopy. Using tilted Fresnel images, contribution of the polarity is introduced into the Fresnel image. However, this contribution is relatively small and a difference image from two symmetrically tilted Fresnel images must be used to eliminate the strong contribution from the in-plane curling magnetization and non-magnetic contrast. The sense of the polarity appears as a bipolar white-black contrast in the difference image on the tilt axis. A vortex core with a diameter of 16.5±2.5nm is experimentally measured. Image tilting, displacement and geometrical distortion may disturb... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175938 Thu, 30 Jun 2011 23:00:00 +0100 5175938 http://www.medworm.com/index.php?rid=5175937&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864769%26dopt%3DAbstract Authors: Vurpillot F, Gruber M, Da Costa G, Martin I, Renaud L, Bostel A Abstract Data collected in atom probe tomography have to be carefully analysed in order to give reliable composition data accurately and precisely positioned in the probed volume. Indeed, the large analysed surfaces of recent instruments require reconstruction methods taking into account not only the tip geometry but also accurate knowledge of geometrical projection parameters. This is particularly crucial in the analysis of multilayers materials or planar interfaces. The current work presents a simulation model that enables extraction of the two main projection features as a function of the tip and atom probe instrumentation geometries. Conversely to standard assumptions, the image compression factor and the ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175937 Thu, 30 Jun 2011 23:00:00 +0100 5175937 http://www.medworm.com/index.php?rid=5175936&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864770%26dopt%3DAbstract Authors: Luo Z, Vasquez Y, Bondi JF, Schaak RE Abstract During the in-situ order-disorder transition of intermetallic L1(2)-type Au(3)Fe(1-x) nanocrystals, structural information has been retrieved from their electron diffraction patterns based on the Pawley refinement that is unrelated to the electron kinematical or dynamical scattering nature as well as the Rietveld refinement using a kinematical approximation. At room temperature, it was found that the nanocrystals contain approximately x=40% vacancies at the Fe site. Based on in-situ heating this phase displayed an irreversible order-disorder transition, with the transition temperature between 553 and 593K. A sudden increase in lattice parameter was detected during the first heating from the ordered phase, while the second heat... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175936 Thu, 30 Jun 2011 23:00:00 +0100 5175936 http://www.medworm.com/index.php?rid=5175935&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864771%26dopt%3DAbstract Authors: Danev R, Nagayama K Abstract Images acquired with a phase plate often exhibit fringing and/or contrast reversal artifacts. The two basic parameters controlling the performance of the phase plate are phase shift and cut-on periodicity. We investigate theoretically and numerically the effect of these parameters on the image quality. The analysis covers not just the typical negative phase shift phase plates but also positive phase shift ones. The theoretical study derives formulas for calculating the optimal phase plate phase shift and for the maximum achievable contrast with a given specimen. Two figures of merit - fidelity and contrast - were defined and used to quantify the numerical results. Larger cut-on periodicities provide better performance with higher contrast and l... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175935 Thu, 30 Jun 2011 23:00:00 +0100 5175935 http://www.medworm.com/index.php?rid=5175934&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864772%26dopt%3DAbstract Authors: Rosenauer A, Mehrtens T, Müller K, Gries K, Schowalter M, Venkata Satyam P, Bley S, Tessarek C, Hommel D, Sebald K, Seyfried M, Gutowski J, Avramescu A, Engl K, Lutgen S Abstract We suggest a method for chemical mapping that is based on scanning transmission electron microscopy (STEM) imaging with a high-angle annular dark field (HAADF) detector. The analysis method uses a comparison of intensity normalized with respect to the incident electron beam with intensity calculated employing the frozen lattice approximation. This procedure is validated with an In(0.07)Ga(0.93)N layer with homogeneous In concentration, where the STEM results were compared with energy filtered imaging, strain state analysis and energy dispersive X-ray analysis. Good agreement was obtained, if the ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175934 Thu, 30 Jun 2011 23:00:00 +0100 5175934 http://www.medworm.com/index.php?rid=5175933&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864773%26dopt%3DAbstract Authors: Hÿtch MJ, Houdellier F, Hüe F, Snoeck E Abstract The genesis, theoretical basis and practical application of the new electron holographic dark-field technique for mapping strain in nanostructures are presented. The development places geometric phase within a unified theoretical framework for phase measurements by electron holography. The total phase of the transmitted and diffracted beams is described as a sum of four contributions: crystalline, electrostatic, magnetic and geometric. Each contribution is outlined briefly and leads to the proposal to measure geometric phase by dark-field electron holography (DFEH). The experimental conditions, phase reconstruction and analysis are detailed for off-axis electron holography using examples from the field of semiconductors. A... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175933 Thu, 30 Jun 2011 23:00:00 +0100 5175933 http://www.medworm.com/index.php?rid=5175932&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864774%26dopt%3DAbstract Authors: Archanjo BS, Maciel IO, Martins Ferreira EH, Peripolli SB, Damasceno JC, Achete CA, Jorio A Abstract This work reports Ga(+) focused ion beam nanopatterning to create amorphous defects with periodic square arrays in highly oriented pyrolytic graphite and the use of Raman spectroscopy as a new protocol to test and compare progresses in ion beam optics, for low fluence bombardment or fast writing speed. This can be ultimately used as a metrological tool for comparing different FIB machines and can contribute to Focused Ion Beam (FIB) development in general for tailoring nanostructures with higher precision. In order to do that, the amount of ion at each spot was varied from about 10(6) down to roughly 1 ion per dot. These defects were also analyzed by using high resolution s... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175932 Thu, 30 Jun 2011 23:00:00 +0100 5175932 http://www.medworm.com/index.php?rid=5175931&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864775%26dopt%3DAbstract Authors: Lahreche A, Beggah Y, Corkish R Abstract The effect of electron range on electron beam induced current (EBIC) is demonstrated and the problem of the choice of the optimal electron ranges to use with simple uniform and point generation function models is resolved by proposing a method to extract an electron range-energy relationship (ERER). The results show that the use of these extracted electron ranges remove the previous disagreement between the EBIC curves computed with simple forms of generation model and those based on a more realistic generation model. The impact of these extracted electron ranges on the extraction of diffusion length, surface recombination velocity and EBIC contrast of defects is discussed. It is also demonstrated that, for the case of uniform gener... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175931 Thu, 30 Jun 2011 23:00:00 +0100 5175931 http://www.medworm.com/index.php?rid=5175930&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864776%26dopt%3DAbstract Authors: Wang A, Chen FR, Van Aert S, Van Dyck D Abstract Reconstructed exit waves are useful to quantify unknown structure parameters such as the position and composition of the atom columns at atomic scale. Existing techniques provide a complex wave in a flat plane which is close to the plane where the electrons leave the atom columns. However, due to local deviation in the flatness of the exit surface, there will be an offset between the plane of reconstruction and the actual exit of a specific atom column. Using the channelling theory, it has been shown that this defocus offset can in principle be determined atom column-by-atom column. As such, the surface roughness could be quantified at atomic scale. However, the outcome strongly depends on the initial plane of reconstruction... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175930 Thu, 30 Jun 2011 23:00:00 +0100 5175930 http://www.medworm.com/index.php?rid=5175929&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864777%26dopt%3DAbstract Authors: Wolny F, Obukhov Y, Mühl T, Weißker U, Philippi S, Leonhardt A, Banerjee P, Reed A, Xiang G, Adur R, Lee I, Hauser AJ, Yang FY, Pelekhov DV, Büchner B, Hammel PC Abstract An iron filled carbon nanotube (FeCNT), a 10-40nm ferromagnetic nanowire enclosed in a protective carbon tube, is an attractive candidate for a magnetic force microscopy (MFM) probe as it provides a mechanically and chemically robust, nanoscale probe. We demonstrate the probe's capabilities with images of the magnetic field gradients close to the surface of a Py dot in both the multi-domain and vortex states. We show the FeCNT probe is accurately described by a single magnetic monopole located at its tip. Its effective magnetic charge is determined by the diameter of the iron wire and its saturation ma... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175929 Thu, 30 Jun 2011 23:00:00 +0100 5175929 http://www.medworm.com/index.php?rid=5175928&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864778%26dopt%3DAbstract Authors: Schwartz GA, Riedel C, Arinero R, Tordjeman P, Alegría A, Colmenero J Abstract In this work we present a new AFM based approach to measure the local dielectric response of polymer films at the nanoscale by means of Amplitude Modulation Electrostatic Force Microscopy (AM-EFM). The proposed experimental method is based on the measurement of the tip-sample force via the detection of the second harmonic component of the photosensor signal by means of a lock-in amplifier. This approach allows reaching unprecedented broad frequency range (2-3×10(4)Hz) without restrictions on the sample environment. The method was tested on different poly(vinyl acetate) (PVAc) films at several temperatures. Simple analytical models for describing the electric tip-sample interaction semi-quantit... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175928 Thu, 30 Jun 2011 23:00:00 +0100 5175928 http://www.medworm.com/index.php?rid=5175927&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864779%26dopt%3DAbstract Authors: Shariq A, Mattern N Abstract Microstructural characterization of Ni(66)Nb(17)Y(17) as spun metallic glass ribbon was carried out using atom probe tomography. A comparison of different experimental conditions for pulsed laser and pulsed voltage field evaporation reveal that the laser pulsing can be optimized to avoid preferential evaporation of yttrium. Atom probe tomography measurements illustrate that the sample undergoes phase separation resulting in two interconnected phases during the process of vitrification. The yttrium-enriched phase was depleted in niobium and yttrium-depleted phase was enriched in niobium. Moreover, detailed analyses of the roller-contact and non-contact sides of the melt-spun ribbon show different wavelength of phase separated regions revealing t... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175927 Thu, 30 Jun 2011 23:00:00 +0100 5175927 http://www.medworm.com/index.php?rid=5175926&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864780%26dopt%3DAbstract Authors: Yi F, Voyles PM Abstract We have explored experimentally the effects of the TEM sample thickness, zero-loss energy filtering, and probe coherence on fluctuation electron microscopy (FEM) experiments implemented using nanodiffraction. FEM measures the variance V of spatial fluctuations in nanodiffraction. We find that V is inversely proportional to the sample thickness, as predicted by earlier models. Energy filtering increases V at all thicknesses we measured. V increases as the coherence of the probe increases. All of these factors must be carefully controlled to obtain quantitatively reliable FEM data. PMID: 21864780 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175926 Thu, 30 Jun 2011 23:00:00 +0100 5175926 http://www.medworm.com/index.php?rid=5175925&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864781%26dopt%3DAbstract Authors: Sato Y, Terauchi M, Mukai M, Kaneyama T, Adachi K Abstract The dielectric properties of LaB(6) crystals and the plasmonic behavior of LaB(6) nanoparticles, which have been applied to solar heat-shielding filters, were studied by high energy-resolution electron energy-loss spectroscopy (HR-EELS). An EELS spectrum of a LaB(6) crystal showed a peak at 2.0eV, which was attributed to volume plasmon excitation of carrier electrons. EELS spectra of single LaB(6) nanoparticles showed peaks at 1.1-1.4eV depending on the dielectric effect from the substrates. The peaks were assigned to dipole oscillation excitations. These peak energies almost coincided with the peak energy of optical absorption of a heat-shielding filter with LaB(6) nanoparticles. On the other hand, those energies ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175925 Thu, 30 Jun 2011 23:00:00 +0100 5175925 http://www.medworm.com/index.php?rid=5175924&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864782%26dopt%3DAbstract Authors: Balantekin M, Değertekin FL Abstract We investigate the optimum driving scheme of a dynamic atomic force microscope with a self-actuated probe for high-speed applications by performing numerical simulations. We compare the recently developed methods such as Q-control, dynamic PID control, and modified Q-control methods to the standard tapping mode by considering scan speed and peak transient forces. In addition, the effects of driving frequency and set-point amplitude on the maximum achievable scan speed for the same probe-sample system are discussed. We find that the scan speed can be increased significantly at the expense of increased peak transient forces. PMID: 21864782 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175924 Thu, 30 Jun 2011 23:00:00 +0100 5175924 http://www.medworm.com/index.php?rid=5175923&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864783%26dopt%3DAbstract Authors: Britton TB, Wilkinson AJ Abstract A set of dynamically simulated electron backscatter patterns (EBSPs) for α-Ti crystals progressively rotated by 1° steps were analysed using cross-correlation to determine image shifts from which strains and rotations were calculated. At larger rotations the cross-correlation fails in certain regions of the EBSP where large shifts are generated. These incorrect shifts prevent standard least square error procedures from obtaining a valid solution for the strain and rotation, where the applied rotation exceeds ∼8°. Using a robust iterative fitting routine reliable strains and rotations can be obtained for applied rotations of up to and including ∼11° even though some image shifts are measured incorrectly. Finally, high resolution ele... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175923 Thu, 30 Jun 2011 23:00:00 +0100 5175923 http://www.medworm.com/index.php?rid=5175922&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864784%26dopt%3DAbstract Authors: Striegler A, Koehler B, Bendjus B, Roellig M, Kopycinska-Mueller M, Meyendorf N Abstract The miniaturization of micro- and nanoelectronic components requires new methods for the inspection of buried inner structures at the nanoscale. We used the atomic force acoustic microscopy technique (AFAM) to image subsurface defects. This technique combines high lateral resolution with the capability to determine local elastic properties of materials near the surface. As the structures buried near the surface change the effective tip-sample contact stiffness it is possible to detect them. For the verification of the detection capabilities of AFAM we fabricated well-defined buried void structures with different geometries and dimensions. Large, thin, plate like structures of silicon n... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175922 Thu, 30 Jun 2011 23:00:00 +0100 5175922 http://www.medworm.com/index.php?rid=5175921&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864785%26dopt%3DAbstract In this study, we combined a recently developed Hopping Probe Ion Conductance Microscopy (HPICM) with patch-clamp technique to investigate the high-resolution morphological changes and functional ion-channel development during the NGF-induced neuronal differentiation of PC12 cells. NGF enlarged TTX-sensitive sodium currents of PC12 cells, which associated with cell volume, membrane surface area, surface roughness of the membrane, and neurite outgrowth. These results demonstrate that the combination of HPICM and patch-clamp technique can provide detailed information of membrane microstructures and ion-channel functions during the differentiation of PC12 cells, and has the potential to become a powerful tool for neuronal research. PMID: 21864785 [PubMed - in process] (Source: Ultramicros... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175921 Thu, 30 Jun 2011 23:00:00 +0100 5175921 http://www.medworm.com/index.php?rid=5175920&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864786%26dopt%3DAbstract Authors: Pishkenari HN, Meghdari A Abstract This paper focuses on the influences of the tip mass ratio (the ratio of the tip mass to the cantilever mass), on the excitation of higher oscillation eigenmodes and also on the tip-sample interaction forces in tapping mode atomic force microscopy (TM-AFM). A precise model for the cantilever dynamics capable of accurate simulations is essential for the investigation of the tip mass effects on the interaction forces. In the present work, the finite element method (FEM) is used for modeling the AFM cantilever to consider the oscillations of higher eigenmodes oscillations. In addition, molecular dynamics (MD) is used to calculate precise data for the tip-sample force as a function of tip vertical position with respect to the sample. The resu... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175920 Thu, 30 Jun 2011 23:00:00 +0100 5175920 http://www.medworm.com/index.php?rid=5175919&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21864787%26dopt%3DAbstract Authors: Maunders C, Dwyer C, Tiemeijer PC, Etheridge J Abstract Two new methods for the measurement of transverse spatial coherence in a transmission electron microscope (TEM) are developed and applied to measure the spatial coherence in a field emission gun TEM. Measurements are made under different illumination and operating conditions, illustrating the effect of these conditions on the spatial coherence. The relative merits and limitations of these methods are discussed and compared, together with the previously described "Ronchigram" method. PMID: 21864787 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5175919 Thu, 30 Jun 2011 23:00:00 +0100 5175919 http://www.medworm.com/index.php?rid=5054606&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21740873%26dopt%3DAbstract Authors: Hoang HQ, Osterberg M, Khursheed A This paper presents a high signal-to-noise ratio electron energy spectrometer attachment for the scanning electron microscope (SEM), designed to measure changes in specimen surface potential from secondary electrons and extract specimen atomic number information from backscattered electrons. Experimental results are presented, which demonstrate that the spectrometer can in principle detect specimen voltage changes well into the sub-mV range, and distinguish close atomic numbers by a signal-to-noise ratio of better than 20. The spectrometer has applications for quantitatively mapping specimen surface voltage and atomic number variations on the nano-scale. PMID: 21740873 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=5054606 Mon, 27 Jun 2011 23:00:00 +0100 5054606 http://www.medworm.com/index.php?rid=4961154&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664546%26dopt%3DAbstract Authors: Koch C, Zuo JM, Chapman H PMID: 21664546 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961154 Tue, 31 May 2011 23:00:00 +0100 4961154 http://www.medworm.com/index.php?rid=4961153&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664547%26dopt%3DAbstract Authors: Koch CT, Zuo JM, Chapman H PMID: 21664547 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961153 Tue, 31 May 2011 23:00:00 +0100 4961153 http://www.medworm.com/index.php?rid=4961152&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664548%26dopt%3DAbstract Authors: Podorov SG, Bishop AI, Paganin DM, Pavlov KM We recently developed a simple closed-form algorithm, which allows one to reconstruct the complex scalar wavefield at the exit surface of a sample, from the intensity of its far-field coherent diffraction pattern which is obtained in the presence of a suitable object-plane mask. In the first variant of this algorithm, the sample is contained within a uniformly illuminated sharp rectangular aperture in which at least one transverse dimension is at least twice that of the object. In the second variant, the sample is uniformly illuminated and is transversely displaced from an opaque rectangular mask in the object plane. For both variants, the far-field diffraction pattern is first Fourier transformed and then differentiated with respec... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961152 Tue, 31 May 2011 23:00:00 +0100 4961152 http://www.medworm.com/index.php?rid=4961151&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664549%26dopt%3DAbstract Authors: Nakashima PN, Moodie AF, Etheridge J The intensity distribution in three-beam CBED patterns from centrosymmetric crystals can be inverted analytically to enable the direct measurement of crystal structure amplitudes and three-phase invariants. The accuracy of the measurements depends upon the accuracy and precision with which specific loci within the discs can be identified. The present work exploits the equivalence in form of the intensity distribution along these loci to provide an algorithm for their automated location, enabling the rapid and unequivocal identification of their position. Moreover, it demonstrates how the loci can be used to determine directly the relative magnitudes of structure amplitudes with superior accuracy and without recourse to complex pattern-match... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961151 Tue, 31 May 2011 23:00:00 +0100 4961151 http://www.medworm.com/index.php?rid=4961150&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664550%26dopt%3DAbstract Authors: Verbeeck J, Bertoni G, Lichte H It has often been stated that a holographic biprism represents a near perfect energy filter and only elastically scattered electrons can participate in the interference fringes. This is based on the assumption that the reference wave does not contain inelastically scattered electrons. In this letter we show that this is not exactly true because of the delocalised inelastic interaction of the reference wave with the sample. We experimentally and theoretically show that inelastic scattering plays a role in the fringe formation, but it is shown that this contribution is small and can usually be neglected in practice. PMID: 21664550 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961150 Tue, 31 May 2011 23:00:00 +0100 4961150 http://www.medworm.com/index.php?rid=4961149&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664551%26dopt%3DAbstract Authors: Van Dyck D Incoherence in electron microscopic imaging occurs when during the observation the microscope and the object are subject to fluctuations. In order to speed up the computer simulation of the images, approximations are used that are considered as valid. In this paper we will question the validity of these approximations and show that in specific cases they can lead to erroneous results. It is shown in particular in the case of one single vibrating atom that the thermal diffuse scattering that causes the signal in HAADF STEM is not only dependent on Z but also on the mean square displacement of the atom so that it can even be large for light atoms in soft matter, provided the right HAADF aperture is used. In HREM imaging the diffuse scattering leaks out of the coherent... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961149 Tue, 31 May 2011 23:00:00 +0100 4961149 http://www.medworm.com/index.php?rid=4961148&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664552%26dopt%3DAbstract Authors: Xu Q, Zandbergen HW, Van Dyck D The knowledge of the valence electron distribution is essential for understanding the properties of materials. However this information is difficult to obtain from HREM images because it is easily obscured by the large scattering contribution of core electrons and by the strong dynamical scattering process. In order to develop a sensitive method to extract the information of valence electrons, we have used an information transmission approach to describe the electron interaction with the object. The scattered electron wave is decomposed in a set of basic functions, which are the eigen functions of the Hamiltonian of the projected electrostatic object potential. Each basic function behaves as a communication channel that transfers the information... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961148 Tue, 31 May 2011 23:00:00 +0100 4961148 http://www.medworm.com/index.php?rid=4961147&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664553%26dopt%3DAbstract Authors: Barthel J, Thust A The precise characterisation of the instrumental imaging properties in the form of aberration parameters constitutes an almost universal necessity in quantitative HRTEM, and is underlying most hardware and software techniques established in this field. We focus in this paper on the numerical analysis of individual diffractograms as a first preparatory step for further publications on HRTEM aberration measurement. The extraction of the defocus and the 2-fold astigmatism from a diffractogram is a classical pattern recognition problem, which we believe to have solved in a near-optimum way concerning precision, speed, and robustness. The newly gained measurement precision allows us to resolve fluctuations of the defocus and the 2-fold astigmatism and to assess t... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961147 Tue, 31 May 2011 23:00:00 +0100 4961147 http://www.medworm.com/index.php?rid=4961146&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664554%26dopt%3DAbstract Authors: Chen Q, Peng LM Using manipulation holders specially designed for transmission electron microscope (TEM), nanostructures can be characterized, measured, modified and even fabricated in-situ. In-situ TEM techniques not only enable real-time study of structure-property relationships of materials at atomic scale, but also provide the ability to control and manipulate materials and structures at nanoscale. This review highlights in-situ electric measurements and in-situ fabrication and structure modification using manipulation holder inside TEM. PMID: 21664554 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961146 Tue, 31 May 2011 23:00:00 +0100 4961146 http://www.medworm.com/index.php?rid=4961164&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664536%26dopt%3DAbstract Authors: Suchorski Y, Schmitz G PMID: 21664536 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961164 Sat, 30 Apr 2011 23:00:00 +0100 4961164 http://www.medworm.com/index.php?rid=4961163&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664537%26dopt%3DAbstract Authors: Suchorski Y, Schmitz G PMID: 21664537 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961163 Sat, 30 Apr 2011 23:00:00 +0100 4961163 http://www.medworm.com/index.php?rid=4961162&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664538%26dopt%3DAbstract Authors: Suchorski Y, Hupalo MS Coadsorption of lithium and oxygen on a nanosized W-tip is studied using field ion appearance energy spectroscopy (FIAES). Binding energies of coadsorbed Li-adatoms are derived locally for chosen atomic sites on (112) facets for different oxygen and Li-coverages. Independently, the binding energies of Li-adatoms in coadsorbed Li/oxygen layers are determined for macroscopic W(112) single crystal samples from the adsorption isobars in adsorption-desorption equilibrium experiments and compared with the local nm-scale measurements. The comparison reveals a very good agreement of results obtained by two different methods on differing length scales. PMID: 21664538 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961162 Sat, 30 Apr 2011 23:00:00 +0100 4961162 http://www.medworm.com/index.php?rid=4961161&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664539%26dopt%3DAbstract This study uses macroscopic electrostatic principles and finite element modelling to investigate field-induced stresses in relation to the shape of the tip. Three two-dimensional idealized models are considered, namely hyperbolic, parabolic and sphere-on-orthogonal-cone; the shapes of which are compared to experimental tips prepared by electro-polishing. Three dimensional morphologies of both a nano-porous and single-crystal aluminium tip are measured using electron tomography to quantitatively test the assumption of cylindrical symmetry for electro-polished tips. The porous tip was prepared and studied to demonstrate a fragile specimen for which such finite element studies could determine potential mechanical failure, prior to any exhaustive atom probe investigation. PMID: 21664539 [P... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961161 Sat, 30 Apr 2011 23:00:00 +0100 4961161 http://www.medworm.com/index.php?rid=4961160&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664540%26dopt%3DAbstract Authors: Nagai S, Sakakibara H, Hata K, Okada M, Mimura H A 90° sector type spin rotator was developed for measurement of the z-direction component of a spin polarization, which is parallel to the emitter axis. The rotator enables us to measure all components of electron spins field-emitted from a single crystalline magnetite. In-plane component of spin polarization dominated of field-emitted electrons from single crystalline magnetite whisker, thus it is suggested that the magnetization of the magnetite whisker results from the anisotropy of crystalline structure rather than its shape. PMID: 21664540 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961160 Sat, 30 Apr 2011 23:00:00 +0100 4961160 http://www.medworm.com/index.php?rid=4961159&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664541%26dopt%3DAbstract Authors: Torres KL, Daniil M, Willard MA, Thompson GB A methodology for determining the optimal voxel size for phase thresholding in nanostructured materials was developed using an atom simulator and a model system of a fixed two-phase composition and volume fraction. The voxel size range was banded by the atom count within each voxel. Some voxel edge lengths were found to be too large, resulting in an averaging of compositional fluctuations; others were too small with concomitant decreases in the signal-to-noise ratio for phase identification. The simulated methodology was then applied to the more complex experimentally determined data set collected from a (Co(0.95)Fe(0.05))(88)Zr(6)Hf(1)B(4)Cu(1) two-phase nanocomposite alloy to validate the approach. In this alloy, Zr and Hf segrega... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961159 Sat, 30 Apr 2011 23:00:00 +0100 4961159 http://www.medworm.com/index.php?rid=4961158&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664542%26dopt%3DAbstract Authors: Miller MK, Longstreth-Spoor L, Kelton KF A combination of simulated and experimental data has been used to investigate the size range of nanovoids that can be detected in atom probe tomography data. Simulated atom probe tomography data have revealed that nanovoids as small as 1nm in diameter can be detected in atom probe tomography data with the use of iso-density surfaces. Iso-density surfaces may be used to quantify the size, morphology and number density of nanovoids and other variations in density in atom probe tomography data. Experimental data from an aluminum-yttrium-iron metallic glass ribbon have revealed the effectiveness of this approach. Combining iso-density surfaces with atom maps also permits the segregation of solute to the nanovoids to be investigated. Field i... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961158 Sat, 30 Apr 2011 23:00:00 +0100 4961158 http://www.medworm.com/index.php?rid=4961157&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664543%26dopt%3DAbstract Authors: Weidow J, Andrén HO A method for quickly producing sharp and site-specific atom probe specimens from WC-Co based cemented carbides was developed using a combination of electropolishing, controlled back-polishing and FIB milling. Also, a method for measuring the amount of segregated atoms to an interface between two phases with a big difference in field needed for field evaporation was developed. Using atom probe tomography, the interface chemistry of WC/WC grain boundaries, WC/(M,W)C phase boundaries and WC/binder phase boundaries was analysed. In addition, the transition metal solubility in WC was determined. PMID: 21664543 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961157 Sat, 30 Apr 2011 23:00:00 +0100 4961157 http://www.medworm.com/index.php?rid=4961156&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664544%26dopt%3DAbstract Authors: Angseryd J, Liu F, Andrén HO, Gerstl SS, Thuvander M A specially produced Ti(C,N) standard material, with a known nominal composition, was investigated with laser assisted atom probe tomography. The occurrence of molecular ions and single/multiple events was found to be influenced by the laser pulse energy, and especially C related events were affected. Primarily two issues were considered when the composition of Ti(C,N) was determined. The first one is connected to detector efficiency, due to the detector dead-time. The second one is connected to peak overlap in the mass spectrum. A method is proposed for quantification of the C content in order to establish the C/N ratio. A correction was made to the major C peaks, C at 6 and 12Da, with the (13)C isotopes, at 6.5 and 13Da, ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961156 Sat, 30 Apr 2011 23:00:00 +0100 4961156 http://www.medworm.com/index.php?rid=4961155&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21664545%26dopt%3DAbstract Authors: Wille CG, Al-Kassab T, Kirchheim R Being widely accessible as well as already utilised in many applications, Fe-Cu acts as an ideal binary model alloy to elaborate the enforced nonequilibrium enhanced solubility in such a solution system that shows a limited regime of miscibility and characterised by a large positive heat of mixing. In addition to the detailed analysis of ball milled Fe-Cu powders by means of Atom Probe Tomography (APT), site specific structural analysis has been performed in this study using Transmission Electron Microscopy (TEM). In this contribution results on powders with low Cu concentrations (2.5-10at%) are presented. Combining a ductile element (Cu, fcc) and a brittle one (Fe, bcc), striking differences in morphology were expected and found on all lengt... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4961155 Sat, 30 Apr 2011 23:00:00 +0100 4961155 http://www.medworm.com/index.php?rid=4643386&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21396523%26dopt%3DAbstract Authors: Yamazaki T, Kotaka Y, Kataoka Y We analyzed a Si/SiO(2) interface using multivariate analysis and spherical aberration-corrected scanning transmission electron microscopy-electron energy loss spectroscopy which is characterized by using the electron energy loss spectrum of the low-loss region. We extracted the low-loss spectra of Si, SiO(2) and an interface state. Even if the interface is formed from materials with different dielectric functions, the present method will prove suitable for obtaining a more quantitative understanding of the dielectric characteristic. PMID: 21396523 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4643386 Tue, 29 Mar 2011 09:45:27 +0100 4643386 http://www.medworm.com/index.php?rid=4643385&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21396524%26dopt%3DAbstract Authors: Chen B, Flewitt PE, Smith DJ, Jones CP Inter-granular creep cavitation damage has been observed in an ex-service 316H austenitic stainless steel thick section weldment. Focused ion beam cross-section milling combined with ion channelling contrast imaging is used to identify the cavitation damage, which is usually associated with the grain boundary carbide precipitates in this material. The results demonstrate that this technique can identify, in particular, the early stage of grain boundary creep cavitation unambiguously in materials with complex phase constituents. PMID: 21396524 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4643385 Tue, 29 Mar 2011 09:45:23 +0100 4643385 http://www.medworm.com/index.php?rid=4643384&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21396525%26dopt%3DAbstract Authors: Ji Y, Wang L, Zhang Y, Wei B, Wang J, Cheng Y, Suo H Electron backscatter diffraction (EBSD) was used for distinguishing crystallographic orientations and local lattice misfits of a La(2)Zr(2)O(7) (LZO) buffer layer epitaxially grown on a cube textured Ni-5.%W (Ni-W) substrate for a YBCO superconductor film. Orientation data were obtained from the LZO epilayer using low energy primary electrons (5keV) and from the Ni-W substrate by increasing the voltage to 15keV. In-plane and out-of-plane orientations of the LZO epilayer were revealed with respect to its Ni-W substrate. A strong {100} 〈011〉 rotated-cube texture in the LZO epilayer was formed on the {100} 〈001〉 cube-textured Ni-W substrates. LZO and Ni in-plane crystallographic axes are related by an expected 45° rota... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4643384 Tue, 29 Mar 2011 09:45:19 +0100 4643384 http://www.medworm.com/index.php?rid=4643383&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21396526%26dopt%3DAbstract Authors: Mingard K, Day A, Maurice C, Quested P For precise orientation and strain measurements, advanced Electron Backscatter Diffraction (EBSD) techniques require both accurate calibration and reproducible measurement of the system geometry. In many cases the pattern centre (PC) needs to be determined to sub-pixel accuracy. The mechanical insertion/retraction, through the Scanning Electron Microscope (SEM) chamber wall, of the electron sensitive part of modern EBSD detectors also causes alignment and positioning problems and requires frequent monitoring of the PC. Optical alignment and lens distortion issues within the scintillator, lens and charge-coupled device (CCD) camera combination of an EBSD detector need accurate measurement for each individual EBSD system. This paper highlig... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4643383 Tue, 29 Mar 2011 09:45:15 +0100 4643383 http://www.medworm.com/index.php?rid=4643382&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21396527%26dopt%3DAbstract Authors: Heidari Mezerji H, Van den Broek W, Bals S It is not straightforward to determine resolution for a 3D reconstruction when performing an electron tomography experiment. Different contributions such as missing wedge and misalignment add up and often influence the final resolution in an anisotropic manner. The conventional resolution measures can not be used for all of the reconstruction techniques, especially for iterative techniques which are more commonly used for electron tomography in materials science. Here we define a quantitative resolution measure that determines the resolution in three orthogonal directions of the reconstruction. As an application we use this measure to determine the optimum number of simultaneous iterative reconstruction technique (SIRT) iterations to ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4643382 Tue, 29 Mar 2011 09:45:11 +0100 4643382 http://www.medworm.com/index.php?rid=4643381&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21396528%26dopt%3DAbstract Authors: Liu BH, Chang DB We proposed and demonstrated a flexible and effective method to design and fabricate scanning probes for atomic force microscopy applications. Computer simulations were adopted to evaluate design specifications and desired performance of atomic force microscope (AFM) probes; the fabrication processes were guided by feedback from simulation results. Through design-simulation-fabrication iterations, tipless cantilevers and tapping mode probes were successfully made with errors as low as 2% in designed resonant frequencies. For tapping mode probes, the probe tip apex achieved a 10nm radius of curvature without additional sharpening steps; tilt-compensated probes were also fabricated for better scanning performance. This method provides AFM users improved probe qu... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4643381 Tue, 29 Mar 2011 09:45:07 +0100 4643381 http://www.medworm.com/index.php?rid=4528202&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21329648%26dopt%3DAbstract Authors: Rhinow D, Büenfeld M, Weber NE, Beyer A, Gölzhäuser A, Kühlbrandt W, Hampp N, Turchanin A Ultrathin carbon nanomembranes (CNM) comprising crosslinked biphenyl precursors have been tested as support films for energy-filtered transmission electron microscopy (EFTEM) of biological specimens. Due to their high transparency CNM are ideal substrates for electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) of stained and unstained biological samples. Virtually background-free elemental maps of tobacco mosaic virus (TMV) and ferritin have been obtained from samples supported by ∼1nm thin CNM. Furthermore, we have tested conductive carbon nanomembranes (cCNM) comprising nanocrystalline graphene, obtained by thermal treatment of CNM, as supports for cr... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528202 Tue, 01 Feb 2011 00:00:00 +0100 4528202 http://www.medworm.com/index.php?rid=4528201&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333852%26dopt%3DAbstract Authors: PMID: 21333852 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528201 Tue, 01 Feb 2011 00:00:00 +0100 4528201 http://www.medworm.com/index.php?rid=4528199&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333854%26dopt%3DAbstract Authors: Crozier PA, Chenna S We have developed methods for using in situ electron energy-loss spectroscopy (EELS) to perform quantitative analysis of gas in an environmental transmission electron microscope. Inner-shell EELS was able to successfully determine the composition of gas mixtures with an accuracy of about 15% or better provided that some precautions are taken during the acquisition to account for the extended gas path lengths associated with the reaction cell. The unique valence-loss spectrum associated with many gases allowed simple methodologies to be developed to determine gas composition from the low-loss region of the spectrum from a gas mixture. The advantage of the valence loss approach is that it allows hydrogen to be detected and quantified. EELS allows real-time a... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528199 Tue, 01 Feb 2011 00:00:00 +0100 4528199 http://www.medworm.com/index.php?rid=4528198&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333855%26dopt%3DAbstract Authors: Castellanos-Gomez A, Agraït N, Rubio-Bollinger G We have studied the dynamics of quartz tuning fork resonators used in atomic force microscopy taking into account the mechanical energy dissipation through the attachment of the tuning fork base. We find that the tuning fork resonator quality factor changes even in the case of a purely elastic sensor-sample interaction. This is due to the effective mechanical imbalance of the tuning fork prongs induced by the sensor-sample force gradient, which in turn has an impact on dissipation through the attachment of the resonator base. This effect may yield a measured dissipation signal that can be different from the one exclusively related to the dissipation between the sensor and the sample. We also find that there is a second-order te... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528198 Tue, 01 Feb 2011 00:00:00 +0100 4528198 http://www.medworm.com/index.php?rid=4528197&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333856%26dopt%3DAbstract Authors: Kim S, Jeong Park M, Balsara NP, Liu G, Minor AM Focused ion beam (FIB) instruments have proven to be an invaluable tool for transmission electron microscopy (TEM) sample preparation. FIBs enable relatively easy and site-specific cross-sectioning of different classes of materials. However, damage mechanisms due to ion bombardment and possible beam heating effects in materials limit the usefulness of FIBs. Materials with adequate heat conductivity do not suffer from beam heating during FIB preparation, and artifacts in materials such as metals and ceramics are primarily limited to defect generation and Ga implantation. However, in materials such as polymers or biological structures, where heat conductivity is low, beam heating can also be a problem. In order to examine FIB dama... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528197 Tue, 01 Feb 2011 00:00:00 +0100 4528197 http://www.medworm.com/index.php?rid=4528195&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333857%26dopt%3DAbstract Authors: Lefebvre W, Philippe T, Vurpillot F This work presents an original method for cluster selection in Atom Probe Tomography designed to be applied to large datasets. It is based on the calculation of the Delaunay tessellation generated by the distribution of atoms of a selected element. It requires a single input parameter from the user. Furthermore, no prior knowledge of the material is needed. The sensitivity of the proposed Delaunay cluster selection is demonstrated by its application on simulated APT datasets. A strong advantage of the proposed methodology is that it is reinforced by the availability of an analytical model for the distribution of Delaunay cells circumspheres, which is used to control the accuracy of the cluster selection procedure. Another advantage of the De... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528195 Tue, 01 Feb 2011 00:00:00 +0100 4528195 http://www.medworm.com/index.php?rid=4528194&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333858%26dopt%3DAbstract Authors: Bennett SE, Ulfig RM, Clifton PH, Kappers MJ, Barnard JS, Humphreys CJ, Oliver RA The electronic characteristics of semiconductor-based devices are greatly affected by the local dopant atom distribution. In Mg-doped GaN, the clustering of dopants at structural defects has been widely reported, and can significantly affect p-type conductivity. We have studied a Mg-doped AlGaN/GaN superlattice using transmission electron microscopy (TEM) and atom probe tomography (APT). Pyramidal inversion domains were observed in the TEM and the compositional variations of the dopant atoms associated with those defects have been studied using APT. Rarely has APT been used to assess the compositional variations present due to structural defects in semiconductors. Here, TEM and APT are used in a ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528194 Tue, 01 Feb 2011 00:00:00 +0100 4528194 http://www.medworm.com/index.php?rid=4528186&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333859%26dopt%3DAbstract Authors: Mendis BG, Craven AJ A method for extracting core and shell spectra from core-shell particles with varying core to shell volume fractions is described. The method extracts the information from a single EELS spectrum image of the particle. The distribution of O and N was correctly reproduced for a nanoparticle with a TiN core and Ti-oxide shell. In addition, the O distribution from a nanoparticle with a Cu core and a Cu-oxide shell was obtained, and the extracted Cu L(2,3)-core and shell spectra showed the required change in EELS near edge fine structure. The extracted spectra can be used for multiple linear least squares fitting to the raw data in the spectrum image. The effect of certain approximations on numerical accuracy, such as treating the nanoparticle as a perfect sphe... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528186 Tue, 01 Feb 2011 00:00:00 +0100 4528186 http://www.medworm.com/index.php?rid=4528185&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333860%26dopt%3DAbstract Authors: Béché A, Rouvière JL, Barnes JP, Cooper D Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. PMID: 21333860 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528185 Tue, 01 Feb 2011 00:00:00 +0100 4528185 http://www.medworm.com/index.php?rid=4528184&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333861%26dopt%3DAbstract Authors: Allen FI, Watanabe M, Lee Z, Balsara NP, Minor AM Energy-filtered transmission electron microscopy spectrum-imaging (EFTEM SI) in the low electron energy-loss range is a valuable technique for probing the chemical structure of a material with nanoscale spatial resolution using a reduced electron dose. By analyzing EFTEM SI datasets using principal component analysis (PCA), the constituent chemical phases of the material can be identified in an efficient manner without prior knowledge of the specimen. We implement low-loss EFTEM SI together with PCA to investigate thin films of the block copolymer electrolyte poly(styrene-block-ethylene oxide) (PS-b-PEO) blended with a sodium salt. PCA identifies three main phases, the first and second phases corresponding to the two blocks of ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528184 Tue, 01 Feb 2011 00:00:00 +0100 4528184 http://www.medworm.com/index.php?rid=4528183&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333862%26dopt%3DAbstract Authors: Garbrecht M, Spiecker E, Tillmann K, Jäger W Aberration-corrected HRTEM is applied to explore the potential of NCSI contrast imaging to quantitatively analyse the complex atomic structure of misfit layered compounds and their incommensurate interfaces. Using the (PbS)(1.14)NbS(2) misfit layered compound as a model system it is shown that atom column position analyses at the incommensurate interfaces can be performed with precisions reaching a statistical accuracy of ±6pm. The procedure adopted for these studies compares experimental images taken from compound regions free of defects and interface modulations with a structure model derived from XRD experiments and with multi-slice image simulations for the corresponding NCSI contrast conditions used. The high precision achiev... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528183 Tue, 01 Feb 2011 00:00:00 +0100 4528183 http://www.medworm.com/index.php?rid=4528181&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21333863%26dopt%3DAbstract Authors: Sarahan MC, Chi M, Masiel DJ, Browning ND Quantitative analysis of point defects is demonstrated through the use of multivariate statistical analysis. This analysis consists of principal component analysis for dimensional estimation and reduction, followed by independent component analysis to obtain physically meaningful, statistically independent factor images. Results from these analyses are presented in the form of factor images and scores. Factor images show characteristic intensity variations corresponding to physical structure changes, while scores relate how much those variations are present in the original data. The application of this technique is demonstrated on a set of experimental images of dislocation cores along a low-angle tilt grain boundary in strontium titan... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4528181 Tue, 01 Feb 2011 00:00:00 +0100 4528181 http://www.medworm.com/index.php?rid=4473185&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21296502%26dopt%3DAbstract We report on the characterization of a high brightness gaseous field ion source using an emitter made of a NiAl needle containing tiny spherical tungsten-carbon precipitates. By field evaporation of such a multiphase alloy, a surface protrusion is formed out of a precipitate, which can act as a small source size field ion emitter. The emission current-voltage characteristics of this emitter were recorded for a variety of parameters. The results obtained suggest that its application as a stable ion source is possible even on long term operation. PMID: 21296502 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4473185 Sat, 22 Jan 2011 00:00:00 +0100 4473185 http://www.medworm.com/index.php?rid=4473186&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21295914%26dopt%3DAbstract Authors: Viskari L, Stiller K Atom probe tomography (APT) allows near atomic scale compositional- and morphological studies of, e.g. matrix, precipitates and interfaces in a wide range of materials. In this work two Ni-base superalloys with similar compositions, Alloy 718 and its derivative Allvac 718Plus, are subject for investigation with special emphasis on the latter alloy. The structural and chemical nuances of these alloys are important for their properties. Of special interest are grain boundaries as their structure and chemistry are important for the materials' ability to resist rapid environmentally induced crack propagation. APT has proved to be suitable for analyses of these types of alloys using voltage pulsed APT. However, for investigations of specimens containing grain b... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4473186 Wed, 19 Jan 2011 00:00:00 +0100 4473186 http://www.medworm.com/index.php?rid=4473188&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21288644%26dopt%3DAbstract Authors: Kambham AK, Mody J, Gilbert M, Koelling S, Vandervorst W With the continuous shrinking of transistors and advent of new transistor architectures to keep in pace with Moore's law and ITRS goals, there is a rising interest in multigate 3D-devices like FinFETs where the channel is surrounded by gates on multiple surfaces. The performance of these devices depends on the dimensions and the spatial distribution of dopants in source/drain regions of the device. As a result there is a need for new metrology approach/technique to characterize quantitatively the dopant distribution in these devices with nanometer precision in 3D. In recent years, atom probe tomography (APT) has shown its ability to analyze semiconductor and thin insulator materials effectively with sub-nm resolution in ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4473188 Tue, 18 Jan 2011 00:00:00 +0100 4473188 http://www.medworm.com/index.php?rid=4473187&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21292398%26dopt%3DAbstract Authors: Kobayashi Y, Takahashi J, Kawakami K The distribution of carbon in atom probe tomography maps was investigated in various phases of steel. Carbon atoms in 3D atom maps of martensite and cementite phases showed an almost uniform distribution. On the other hand, carbon atoms in ferrite were consistently enriched along the zone line joining the (002) and the (222) poles, and in the depth direction of analysis, which was different from the actual distribution. The width and concentration of the enriched regions remained unchanged at a specimen temperature ranging from 90to 30K. Moreover, the ratio of molecular carbon ions to total carbon ions decreased with decreasing temperature, but did not change between the enriched and diluted regions. Based on the results, the reason for the... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4473187 Tue, 18 Jan 2011 00:00:00 +0100 4473187 http://www.medworm.com/index.php?rid=4473189&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21288642%26dopt%3DAbstract Authors: Tajmar M, Vasiljevich I, Grienauer W We recently developed an indium Liquid-Metal-Ion-Source that can emit currents from sub-μA up to several mA. It is based on a porous tungsten crown structure with 28 individual emitters, which is manufactured using Micro-Powder Injection Molding (μPIM) and electrochemical etching. The emitter combines the advantages of internal capillary feeding with excellent emission properties due to micron-size tips. Significant progress was made on the homogeneity of the emission over its current-voltage characteristic as well as on investigating its long-term stability. This LMIS seems very suitable for space propulsion as well as for micro/nano manufacturing applications with greatly increased milling/drilling speeds. This paper summarizes the late... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4473189 Sat, 15 Jan 2011 00:00:00 +0100 4473189 http://www.medworm.com/index.php?rid=4406419&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21255930%26dopt%3DAbstract Authors: Ha Dzel P, Jurczyszyn L, Kucharczyk R Photofield emission (PFE) measurements are employed to examine modifications of the surface electronic structure of the tungsten (111) facet upon deposition of thin films (1-3 monolayers) of titanium. With the help of DFT simulations, the observed PFE features are interpreted as adsorbate-induced resonance states with energies just below the Fermi level, localized predominantly at the exposed surface atoms. Comparison between the computed surface DOS distributions and the measured PFE spectra is also used to verify various possible arrangements of the Ti adatoms, supporting the DFT-favored model of Ti growth in registry with the W(111) substrate until a full physical overlayer of the adsorbate is completed. PMID: 21255930 [PubMed - as ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4406419 Sat, 15 Jan 2011 00:00:00 +0100 4406419 http://www.medworm.com/index.php?rid=4406418&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21257265%26dopt%3DAbstract Authors: Sonestedt M, Stiller K Ti(2)AlC belongs to an interesting group of materials with both metallic and ceramic properties. This material is highly attractive as a candidate for corrosion resistant coatings. The process of fabrication of such coatings is in the investigation stage only and the detailed knowledge of the structure and chemistry of the produced coatings is important for optimisation of their properties. In this work the applicability of atom probe tomography for investigation of both Ti(2)AlC bulk materials and coatings was tested. We show that for the first time, Ti(2)AlC has successfully been analysed using laser pulsing mode in a local electrode atom probe and the results from analysis of both bulk Ti(2)AlC and Ti(2)AlC based spray deposited coatings are presented... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4406418 Fri, 07 Jan 2011 00:00:00 +0100 4406418 http://www.medworm.com/index.php?rid=4406421&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21227591%26dopt%3DAbstract Authors: Ziaja B, Martin AV, Wang F, Chapman HN, Weckert E Coherent diffraction imaging of single biomolecules is expected to open unique opportunities for studies of non-crystalline samples. There are, however, still many technical and physical issues that need to be resolved in a more quantitative manner, especially if one aims for structural information at high resolution. Signal recorded from an object after a single shot is low. As primarily proposed in Spence and Doak (2004) and Huldt et al. (2003) [1,2], averaging over the diffraction patterns from many different shots is necessary, in order to achieve a signal-to-noise ratio sufficient for image reconstruction. The images of the randomly oriented molecules have to be sorted out in order to identify those corresponding to the si... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4406421 Wed, 05 Jan 2011 00:00:00 +0100 4406421 http://www.medworm.com/index.php?rid=4406420&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21232865%26dopt%3DAbstract Authors: Hyde JM, Burke MG, Gault B, Saxey DW, Styman P, Wilford KB, Williams TJ In this work, the importance of optimising experimental conditions for the analysis of reactor pressure vessel (RPV) steels using atom probe tomography is explored. The quality of the resultant atom probe data is assessed in terms of detection efficiency, noise levels and mass resolution. It is demonstrated that artefacts can exist even when experimental conditions have been optimised. In particular, it is shown that surface diffusion of some minority species, including P and Si, to major poles prior to field evaporation can be an issue. The effects were most noticeable during laser pulsing. The impact of surface migration on the characterisation of dislocations and grain boundaries is assessed. The import... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4406420 Tue, 04 Jan 2011 00:00:00 +0100 4406420 http://www.medworm.com/index.php?rid=4342793&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185451%26dopt%3DAbstract Authors: Wachtmeister S, Csillag S Gold's iterative deconvolution algorithm has been applied to one-dimensional EEL spectra from hexagonal BN. The experimental resolution was varied from 1.1 to 2.25 eV and Gold's algorithm was able to restore low-loss and core-loss spectra overall well. To estimate the instrument response function, the most convenient method was to extract the zero-loss peak from the low-loss spectrum. By instead using low-loss spectra as kernel, as suggested by Egerton, enhanced energy resolution could also be obtained with plural scattering simultaneously removed. It is further shown how the FWHM of the π* peak in the boron K-edge of hexagonal BN is reduced from 1.4 to 0.7 eV with almost no noise amplification after 500 iterations while resolving the σ* doublet. Th... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342793 Sat, 01 Jan 2011 00:00:00 +0100 4342793 http://www.medworm.com/index.php?rid=4342792&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185452%26dopt%3DAbstract Authors: Glaeser RM, McMullan G, Faruqi AR, Henderson R Quantitative analysis of electron microscope images of organic and biological two-dimensional crystals has previously shown that the absolute contrast reached only a fraction of that expected theoretically from the electron diffraction amplitudes. The accepted explanation for this is that irradiation of the specimen causes beam-induced charging or movement, which in turn causes blurring of the image due to image or specimen movement. In this paper, we used three different approaches to try to overcome this image-blurring problem in monolayer crystals of paraffin. Our first approach was to use an extreme form of spotscan imaging, in which a single image was assembled on film by the successive illumination of up to 50,000 spots, eac... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342792 Sat, 01 Jan 2011 00:00:00 +0100 4342792 http://www.medworm.com/index.php?rid=4342791&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185453%26dopt%3DAbstract Authors: Cervera Gontard L, Ozkaya D, Dunin-Borkowski RE Nanoparticles have a wide range of applications in science and technology. Their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we describe a simple computer algorithm for measuring particle size distributions from TEM images in the presence of an uneven background. The approach is based on adaptive thresholding, making use of local threshold values that change with spatial coordinate. The algorithm allows particles to be detected and characterized with greater accuracy than using more conventional methods, in which a global threshold is used. Its application to images of heterogeneous catalysts is presented. PMID: 21185453 [PubMed - in process] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342791 Sat, 01 Jan 2011 00:00:00 +0100 4342791 http://www.medworm.com/index.php?rid=4342790&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185454%26dopt%3DAbstract Authors: Pishkenari HN, Meghdari A The finite element method and molecular dynamics simulations are used for modeling the AFM microcantilever dynamics and the tip-sample interaction forces, respectively. Molecular dynamics simulations are conducted to calculate the tip-sample force data as a function of tip height at different lateral positions of the tip with respect to the sample. The results demonstrate that in the presence of nonlinear interaction forces, higher eigenmodes of the microcantilever are excited and play a significant role in the tip and sample elastic deformations. Using comparisons between the results of FEM and lumped models, how some aspects of the system behavior can be hidden when the point-mass model is used is illustrated. PMID: 21185454 [PubMed - in process... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342790 Sat, 01 Jan 2011 00:00:00 +0100 4342790 http://www.medworm.com/index.php?rid=4342789&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185455%26dopt%3DAbstract Authors: Li S, Feng Z, Zhang L, Wang Y, Chen L An applicable method to prepare transmission electron microscopy specimens from ceramic fibers for longitudinal and cross-sectional observations is investigated. The method includes novel embedding processes to fix fibers, a polishing process using a self-manufactured device to get uniformly low thickness (40 μm for L-fiber, 60 μm for C-fiber), a one-side dimpling process to grind the specimen to near electron transparency (about 5 μm in thickness for both L-fiber and C-fiber) and an efficient ion milling process using calculated parameters. These techniques are reliable to accomplish the preparation with high quality in a relatively short time. Many factors related to the preparation processes are discussed. PMID: 21185455 [PubMed ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342789 Sat, 01 Jan 2011 00:00:00 +0100 4342789 http://www.medworm.com/index.php?rid=4342788&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185456%26dopt%3DAbstract Authors: Ni N, Lozano-Perez S, Sykes J, Grovenor C Zirconium alloys have been long used for fuel cladding and other structural components in water-cooled nuclear reactors, but waterside corrosion is a primary limitation on both high fuel burn-up and extended fuel cycle operation. Understanding the processes that occur at the metal/oxide interface is crucial for a full mechanistic description of the oxidation process. In this paper we show that reliable quantification of the oxygen content at the metal/oxide interface can be obtained by Electron Energy Loss Spectrometry (EELS) if enough care is taken over both the preparation of Transmission Electron Microscopy (TEM) samples and the methodology for quantification of the EELS data. We have reviewed the accuracy of theoretically calculate... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342788 Sat, 01 Jan 2011 00:00:00 +0100 4342788 http://www.medworm.com/index.php?rid=4342787&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185457%26dopt%3DAbstract Authors: Zhang T, Chao Y, Shih K, Li XY, Fang HH To determine the lateral detachment force for individual bacterial cells, a quantitative method using the contact mode of an atomic force microscope (AFM) was developed in this study. Three key factors for the proposed method, i.e. scan size, scan rate and cantilever choice, were evaluated and optimized. The scan size of 40×40 μm² was optimal for capturing sufficient number of adhered cells in a microscopic field and provide adequate information for cell identification and detachment force measurement. The scan rate affected the measurement results significantly, and was optimized at 40 μm/s considering both force measurement accuracy and experimental efficiency. The hardness of applied cantilevers also influenced force determination... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342787 Sat, 01 Jan 2011 00:00:00 +0100 4342787 http://www.medworm.com/index.php?rid=4342786&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185458%26dopt%3DAbstract Authors: Maurice C, Dzieciol K, Fortunier R The moving screen technique for pattern centre localisation is revisited. A cross-correlation based iterative procedure is developed to find both the zoom factor and the zoom centre (which is also the pattern centre) between two EBSD diffraction patterns acquired at two camera positions. The procedure involves two steps: first, a rough estimate of the pattern centre position and zoom factor (the ratio of the two detector distances) is obtained by cross-correlating the entire images. Then, based on this first estimate, cross-correlation of smaller regions of interest (ROIs) gives the displacement field which is interpreted as a zoom factor misfit coupled with a zoom centre position misfit. These misfits are iteratively decreased until the disp... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342786 Sat, 01 Jan 2011 00:00:00 +0100 4342786 http://www.medworm.com/index.php?rid=4342785&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185459%26dopt%3DAbstract Authors: Valamanesh M, Langlois C, Alloyeau D, Lacaze E, Ricolleau C This paper reports the coupling of HRTEM and moiré pattern observations, allowing the determination of the thickness ratio of two superimposed crystals. Pseudo-lattice fringes are observed using identical TEM experimental conditions as for observing moiré patterns. The pseudo-lattice spacing is first calculated in the dynamical theory framework in two beam conditions. This approach shows a linear behavior of the spacing as a function of the thickness ratio of the two crystals. The roles of sample crystallographic orientation and sample thickness on the thickness ratio determination are discussed from multi-beam simulations. Finally, the method is applied on a bimetallic CuAg core-shell nanoparticle of a known struct... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342785 Sat, 01 Jan 2011 00:00:00 +0100 4342785 http://www.medworm.com/index.php?rid=4342784&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185460%26dopt%3DAbstract Authors: Löffler M, Weissker U, Mühl T, Gemming T, Büchner B Young's modulus of an individual multi-wall carbon nanotube has been determined by the method of quasi-static transverse bending due to a Lorentz force observed in situ in a transmission electron microscope. The deflection of the nanotube allows the determination of Young's modulus using Euler-Bernoulli's beam equation. Because we determine the specific dependence of the deflection on the position along the nanotube axis, it is possible to gain insight into the type of mountings and furthermore allows for an estimation of the homogeneity of the nanotube. Both properties have been found to be of importance to determine Young's modulus. It was found to be higher by up to a factor of 1.6 compared to the value obtained by assu... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342784 Sat, 01 Jan 2011 00:00:00 +0100 4342784 http://www.medworm.com/index.php?rid=4342783&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185461%26dopt%3DAbstract Authors: Dries M, Schultheiss K, Gamm B, Rosenauer A, Schröder RR, Gerthsen D Transmission electron microscopy phase-contrast images taken by amorphous carbon film-based phase plates are affected by the scattering of electrons within the carbon film causing a modification of the image-wave function. Moreover, image artefacts are produced by non-centrosymmetric phase plate designs such as the Hilbert-phase plate. Various methods are presented to correct phase-contrast images with respect to the scattering of electrons and image artefacts induced by phase plates. The proposed techniques are not restricted to weak-phase objects and linear image formation. Phase-contrast images corrected by the presented methods correspond to those taken by an ideal centrosymmetric, matter-free phase plat... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342783 Sat, 01 Jan 2011 00:00:00 +0100 4342783 http://www.medworm.com/index.php?rid=4342782&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21185462%26dopt%3DAbstract Authors: de la Peña F, Berger MH, Hochepied JF, Dynys F, Stephan O, Walls M We study materials that present challenges for conventional elemental mapping techniques and can in some cases be treated successfully using independent component analysis (ICA). In this case the material in question is obtained from a TiO₂-SiO₂ solid solution that is spinodally decomposed into TiO₂ rich-SnO₂ rich multilayers. Conventional elemental mapping is difficult because the edges most easily mapped for these elements (Ti-L, Sn-M and O-K) all have onsets within the same 80 eV range. ICA is used to separate entire spectral signals corresponding to particular material phases or molecular units rather than particular elements and is thus able to distinguish between TiO₂ and SnO₂. We show that q... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342782 Sat, 01 Jan 2011 00:00:00 +0100 4342782 http://www.medworm.com/index.php?rid=4342778&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215521%26dopt%3DAbstract In this study, atom probe tomography (APT) has been used to quantitatively characterise the evolution of the GP zones and the solute distribution in the bimodal microstructure as a function of applied plastic strain. Recent nuclear magnetic resonance (NMR) analysis has clearly shown strain-induced dissolution of the GP zones, which is supported by the current APT data with additional spatial information. There is significant repartitioning of Cu from the GP zones into the solid solution during deformation. A new approach for cluster finding in APT data has been used to quantitatively characterise the evolution of the sizes and shapes of the Cu containing features in the solid solution solute as a function of applied strain. PMID: 21215521 [PubMed - as supplied by publisher] (Source: Ul... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342778 Wed, 29 Dec 2010 00:00:00 +0100 4342778 http://www.medworm.com/index.php?rid=4342773&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21216102%26dopt%3DAbstract Authors: Etienne A, Radiguet B, Cunningham NJ, Odette GR, Valiev R, Pareige P Due to a high number density of grain boundaries acting as point defect sinks, ultrafine-grained materials are expected to be more resistant to irradiation damage. In this context, ultrafine-grained 316 austenitic stainless steel samples have been fabricated by high pressure torsion. Their behavior under ion irradiation has been studied using atom probe tomography. Results are compared with those obtained in an ion irradiated conventional coarse-grained steel. The comparison shows that the effects of irradiation are limited and that intragranular and intergranular features are smaller in the ultrafine-grained alloy. Using cluster dynamic modeling, results are interpreted by a higher annihilation of point defe... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342773 Tue, 28 Dec 2010 00:00:00 +0100 4342773 http://www.medworm.com/index.php?rid=4342777&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215522%26dopt%3DAbstract Authors: Larson DJ, Prosa TJ, Geiser BP, Egelhoff WF The accuracy and precision of thin-film interfacial mixing as measured with atom probe tomography (APT) are assessed by considering experimental and simulated field-evaporation of a Co/Cu/Co multilayer structure. Reconstructions were performed using constant shank angle and Z-scale reordering algorithms. Reconstruction of simulated data (zero intermixing) results in a 10-90% intermixing width of ∼0.2nm while experiential intermixing (measured from multiple runs) was 0.47±0.19 and 0.49±0.10nm for Co-on-Cu and Cu-on-Co interfaces, respectively. The experimental data were collected in analysis orientations both parallel and anti-parallel to film growth direction and the impact of this on the interfacial mixing measurements is discus... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342777 Fri, 24 Dec 2010 00:00:00 +0100 4342777 http://www.medworm.com/index.php?rid=4342781&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21190798%26dopt%3DAbstract Authors: Li F, Ohkubo T, Chen YM, Kodzuka M, Hono K We have investigated the irradiation conditions of femtosecond laser pulses for quantitative atom probe analyses of rare-earth (RE) doped ceria. The influence of laser wavelength, power, pulse frequency, as well as specimen temperature on mass resolution and background noise of atom probe mass spectra were investigated. Furthermore, quantitative atom probe analysis of yttrium distribution in Y-doped ceria was carried out with the optimized evaporation conditions. The distribution of yttrium was found to be uniform within the grains, but they were confirmed to be segregated at grain boundaries. PMID: 21190798 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342781 Wed, 15 Dec 2010 00:00:00 +0100 4342781 http://www.medworm.com/index.php?rid=4342780&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21193267%26dopt%3DAbstract Authors: Parish CM, Capdevila C, Miller MK Multivariate statistical analysis (MVSA) methods, such as used in analytical electron microscopy and surface science, were applied to atom probe tomography (APT) data. It was found that MVSA methods allow fast and intuitive interpretation of APT data, where both spatial and spectral variance are described simultaneously in an unbiased manner. In this work, a Fe-Cr-Al-Ti alloy (PM2000(TM)) subjected to different heat treatments was examined via APT. The different scale three-phase microstructures resulting from these heat treatments provided an interesting test of the capabilities and limits of the present MVSA methodology. Principal component analysis (PCA)-based MVSA identified the precipitate populations in all three samples, including ultra... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342780 Wed, 15 Dec 2010 00:00:00 +0100 4342780 http://www.medworm.com/index.php?rid=4342775&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215524%26dopt%3DAbstract Authors: Dmitrieva O, Choi P, Gerstl SS, Ponge D, Raabe D A precipitation hardened maraging TRIP steel was analyzed using a pulsed laser atom probe. The laser pulse energy was varied from 0.3 to 1.9nJ to study its effect on the measured chemical compositions and spatial resolution. Compositional analyses using proximity histograms did not show any significant variations in the average matrix and precipitate compositions. The only remarkable change in the atom probe data was a decrease in the ++/+ charge state ratios of the elements. The values of the evaporation field used for the reconstructions exhibit a linear dependence on the laser pulse energy. The adjustment of the evaporation fields used in the reconstructions for different laser pulse energies was based on the correlation of t... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342775 Wed, 15 Dec 2010 00:00:00 +0100 4342775 http://www.medworm.com/index.php?rid=4342776&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21215523%26dopt%3DAbstract Authors: Mousa M, Wanderka N, Timpel M, Singh S, Krüger M, Heilmaier M, Banhart J Molybdenum and its alloys are potential materials for high-temperature applications. However, molybdenum is susceptible to embrittlement because of oxygen segregation at the grain boundaries. In order to alleviate the embrittlement small amounts of zirconium were alloyed to a solid solution of Mo-1.5Si alloy. Two Mo-based alloys, namely Mo-1.5Si and Mo-1.5Si-1Zr, were investigated by the complementary high-resolution methods transmission electron microscopy and atom probe tomography. The Mo-1.5Si alloy shows a polycrystalline structure with two silicon-rich intermetallic phases Mo(5)Si(3) and Mo(3)Si located at the grain boundaries and within the grains. In addition, small clusters with up to 10at% Si we... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342776 Tue, 14 Dec 2010 00:00:00 +0100 4342776 http://www.medworm.com/index.php?rid=4342779&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21193268%26dopt%3DAbstract We report on the observability of valence bonding effects in aberration-corrected high resolution electron microscopy (HREM) images along the [010] projection of the mineral Forsterite (Mg(2)SiO(4)). We have also performed exit wave restorations using simulated noisy images and have determined that both the intensities of individual images and the modulus of the restored complex exit wave are most sensitive to bonding effects at a level of 25% for moderately thick samples of 20-25nm. This relatively large thickness is due to dynamical amplification of bonding contrast arising from partial de-channeling of 1s states. Simulations also suggest that bonding contrast is similarly high for an un-corrected conventional electron microscope, implying an experimental limitation of signal to noise ra... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342779 Mon, 13 Dec 2010 00:00:00 +0100 4342779 http://www.medworm.com/index.php?rid=4342774&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21216101%26dopt%3DAbstract Authors: Singh S, Wanderka N, Kiefer K, Siemensmeyer K, Banhart J Splat-quenched, as-cast and aged (2h at 600°C after casting) AlCoCrCuFeNi high entropy alloys were investigated by means of transmission electron microscopy and three-dimensional atom probe (3D-AP). 3D-AP revealed anti-correlated fluctuations of the Cr and Fe-Co compositions in Cr-Fe-Co-rich regions of the as-cast alloy. The ferromagnetic behavior of AlCoCrCuFeNi high entropy alloy was correlated with the decomposition of the Cr-Fe-Co-rich regions into ferromagnetic Fe-Co-rich and antiferromagnetic Cr-rich domains, the size of which was determined by statistical analysis of 3D-AP data. The splat-quenched alloy showed a softer magnetic behavior as compared to the as-cast and aged alloys. The aged alloy possessed a higher... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342774 Fri, 10 Dec 2010 00:00:00 +0100 4342774 http://www.medworm.com/index.php?rid=4342794&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21177036%26dopt%3DAbstract Authors: Hono K, Ohkubo T, Chen YM, Kodzuka M, Oh-Ishi K, Sepehri-Amin H, Li F, Kinno T, Tomiya S, Kanitani Y Laser assisted field evaporation using ultraviolet (UV) wavelength gives rise to better mass resolution and signal-to-noise ratio in atom probe mass spectra of metals, semiconductors and insulators compared to infrared and green lasers. Combined with the site specific specimen preparation techniques using the lift-out and annular Ga ion milling in a focused ion beam machine, a wide variety of materials including insulating oxides can be quantitatively analyzed by the three-dimensional atom probe using UV laser assisted field evaporation. After discussing laser irradiation conditions for optimized atom probe analyses, recent atom probe tomography results on oxides, semiconductor... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4342794 Thu, 02 Dec 2010 00:00:00 +0100 4342794 http://www.medworm.com/index.php?rid=4278035&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21146302%26dopt%3DAbstract Authors: Deponte DP, McKeown JT, Weierstall U, Doak RB, Spence JC A sufficiently thin column of liquid was produced to permit penetration with a 200keV electron beam as evidenced by the observation of diffraction rings due to the intermolecular spacing of the liquid samples. For liquid thickness below 800nm, the diffraction rings became visible above the inelastic background. Studies were carried out in the environmental chamber of a transmission electron microscope using water and isopropanol. PMID: 21146302 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4278035 Wed, 01 Dec 2010 00:00:00 +0100 4278035 http://www.medworm.com/index.php?rid=4278034&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21146934%26dopt%3DAbstract Authors: Tsukada M, Tamura H, McKenna KP, Shluger AL, Chen YM, Ohkubo T, Hono K To explain the recent successful three-dimensional atom probe (3DAP) analyses of insulating oxides by laser assisted field evaporation, we investigated the mechanism of the laser-induced field evaporation of oxides by ab initio calculations. The calculated potential energy surfaces (PESs) for the ground and excited states indicated that the activation barrier height for field evaporation is substantially reduced by the accumulation of holes near the tip apex. This would make the direct electronic excitation possible to promote field evaporation along with thermal excitation. These theoretical calculations are supported by experimental observations. PMID: 21146934 [PubMed - as supplied by publisher] (Sou... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4278034 Wed, 01 Dec 2010 00:00:00 +0100 4278034 http://www.medworm.com/index.php?rid=4278033&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21168272%26dopt%3DAbstract Authors: Poon HC, Saldin DK We amplify on the principles of the method we have recently proposed for recovering an oversampled diffraction pattern of a single particle from measured diffraction patterns from multiple particles in orientations related by rotation about an axis parallel to the incident radiation. We propose an alternative method of phasing a reference resolution ring by means of a non-negativity constraint on the diffraction intensities, point out the need for caution about enantiomeric ambiguities in the reconstruction of a diffraction pattern from its angular correlations, and show that converged correlations may be deduced by appropriate averaging of even very noisy data. PMID: 21168272 [PubMed - as supplied by publisher] (Source: Ultramicroscopy) Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4278033 Wed, 01 Dec 2010 00:00:00 +0100 4278033 http://www.medworm.com/index.php?rid=4220629&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21111260%26dopt%3DAbstract Authors: Tajmar M, Vasiljevich I, Grienauer W We recently developed an indium Liquid-Metal-Ion-Source that can emit currents from sub-μA up to several mA. It is based on a porous tungsten crown structure with 28 individual emitters, which is manufactured using Micro-Powder Injection Molding (μPIM) and electrochemical etching. The emitter combines the advantages of internal capillary feeding with excellent emission properties due to micron-size tips. Significant progress was made on the homogeneity of the emission over its current-voltage characteristic as well as on investigating its long-term stability. This LMIS seems very suitable for space propulsion as well as for micro/nano manufacturing applications with greatly increased milling/drilling speeds. This paper summarizes the late... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4220629 Wed, 01 Dec 2010 00:00:00 +0100 4220629 http://www.medworm.com/index.php?rid=4220628&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21111261%26dopt%3DAbstract Authors: Ha Dzel P, Jurczyszyn L, Kucharczyk R Photofield emission (PFE) measurements are employed to examine modifications of the surface electronic structure of the tungsten (111) facet upon deposition of thin films (1-3 monolayers) of titanium. With the help of DFT simulations, the observed PFE features are interpreted as adsorbate-induced resonance states with energies just below the Fermi level, localized predominantly at the exposed surface atoms. Comparison between the computed surface DOS distributions and the measured PFE spectra is also used to verify various possible arrangements of the Ti adatoms, supporting the DFT-favored model of Ti growth in registry with the W(111) substrate until a full physical overlayer of the adsorbate is completed. PMID: 21111261 [PubMed - in ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4220628 Wed, 01 Dec 2010 00:00:00 +0100 4220628 http://www.medworm.com/index.php?rid=4220627&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21111262%26dopt%3DAbstract We present a new method to improve the accuracy of force application and hardness measurements in hard surfaces by using low-force (<50μN) nanoindentation technique with a cube-corner diamond tip mounted on an atomic force microscopy (AFM) sapphire cantilever. A force calibration procedure based on the force-matching method, which explicitly includes the tip geometry and the tip-substrate deformation during calibration, is proposed. A computer algorithm to automate this calibration procedure is also made available. The proposed methodology is verified experimentally by conducting AFM nanoindentations on fused quartz, Si(100) and a 100-nm-thick film of gold deposited on Si(100). Comparison of experimental results with finite element simulations and literature data yields excellent agree... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4220627 Wed, 01 Dec 2010 00:00:00 +0100 4220627 http://www.medworm.com/index.php?rid=4220626&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21111263%26dopt%3DAbstract Authors: Mitsuishi K, Hashimoto A, Takeguchi M, Shimojo M, Ishizuka K Imaging properties of scanning confocal electron microscopy (SCEM) were studied by calculating simple model systems using the multislice method. A simple geometrical explanation was given, particularly for the difference between bright field (BF) and annular dark field (ADF) SCEM. It is demonstrated that the BF-SCEM image contrast consists of two features. One gradually changes over a wide defocus range and depends on the lateral size of the object. Another appears only near the focus and is independent of sample size. On the contrary, ADF-SCEM image contrast does not depend on the lateral size of the object. Therefore, the ADF-SCEM will provide more readily interpretable image contrast. PMID: 21111263 [PubMed - ... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4220626 Wed, 01 Dec 2010 00:00:00 +0100 4220626 http://www.medworm.com/index.php?rid=4220625&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21111264%26dopt%3DAbstract Authors: Barthel J, Thust A The precise characterisation of the instrumental imaging properties in the form of aberration parameters constitutes an almost universal necessity in quantitative HRTEM, and is underlying most hardware and software techniques established in this field. We focus in this paper on the numerical analysis of individual diffractograms as a first preparatory step for further publications on HRTEM aberration measurement. The extraction of the defocus and the 2-fold astigmatism from a diffractogram is a classical pattern recognition problem, which we believe to have solved in a near-optimum way concerning precision, speed, and robustness. The newly gained measurement precision allows us to resolve fluctuations of the defocus and the 2-fold astigmatism and to assess t... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4220625 Wed, 01 Dec 2010 00:00:00 +0100 4220625 http://www.medworm.com/index.php?rid=4220624&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21115277%26dopt%3DAbstract Authors: Oliver RA To provide a route to the assessment of the impact of inclined facets on unintentional n-type doping during the growth of c-plane GaN on sapphire, thin (100nm), highly Si-doped (at 10(19)cm(-3)) marker layers have been incorporated into a GaN epitaxial layer grown by a method involving a transition from initial three-dimensional island growth to later, two-dimensional, planar growth. Imaging of the completed epitaxial layer in cross-section by scanning capacitance microscopy reveals the shapes of the islands, which were present during the early stages of growth and the relationship between the facets present and the incorporation of unintentional dopants. The results show that unintentional dopants are mostly incorporated on facets inclined to the [0001] direction, a... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4220624 Wed, 01 Dec 2010 00:00:00 +0100 4220624 http://www.medworm.com/index.php?rid=4201915&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21093986%26dopt%3DAbstract Authors: Maia FR, Yang C, Marchesini S Ultrafast nanocrystallography has the potential to revolutionize biology by enabling structural elucidation of proteins for which it is possible to grow crystals with 10 or fewer unit cells on the side. The success of nanocrystallography depends on robust orientation-determination procedures that allow us to average diffraction data from multiple nanocrystals to produce a three-dimensional (3D) diffraction data volume with a high signal-to-noise ratio. Such a 3D diffraction volume can then be phased using standard crystallographic techniques. "Indexing" algorithms used in crystallography enable orientation determination of diffraction data from a single crystal when a relatively large number of reflections are recorded. Here we show that it is pos... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4201915 Tue, 09 Nov 2010 00:00:00 +0100 4201915 http://www.medworm.com/index.php?rid=4201917&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21093151%26dopt%3DAbstract Authors: Elser V The high intensity of free-electron X-ray light sources may enable structure determinations of viruses or even individual proteins without the encumbrance of first forming crystals. This note compares two schemes of non-crystalline diffraction data collection that have been proposed: serial single-shot data from individual particles, and averaged cross-correlation data from particle ensembles. The information content of these schemes is easily compared and we show that the single-shot approach, although experimentally more challenging, is always superior in this respect. In fact, for 3D structure determination a constraint counting argument shows that the cross-correlation scheme suffers from data deficiency. PMID: 21093151 [PubMed - as supplied by publisher] (Sour... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4201917 Thu, 28 Oct 2010 00:00:00 +0100 4201917 http://www.medworm.com/index.php?rid=4201916&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21093152%26dopt%3DAbstract Authors: Wang P, Behan G, Kirkland AI, Nellist PD, Cosgriff EC, D'Alfonso AJ, Morgan AJ, Allen LJ, Hashimoto A, Takeguchi M, Mitsuishi K, Shimojo M Scanning confocal electron microscopy (SCEM) offers a mechanism for three-dimensional imaging of materials, which makes use of the reduced depth of field in an aberration-corrected transmission electron microscope. The simplest configuration of SCEM is the bright-field mode. In this paper we present experimental data and simulations showing the form of bright-field SCEM images. We show that the depth dependence of the three-dimensional image can be explained in terms of two-dimensional images formed in the detector plane. For a crystalline sample, this so-called probe image is shown to be similar to a conventional diffraction pattern. Exper... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4201916 Wed, 27 Oct 2010 00:00:00 +0100 4201916 http://www.medworm.com/index.php?rid=4139816&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21051146%26dopt%3DAbstract Authors: Martin AV, Bishop AI, Paganin DM, Allen LJ We experimentally implement a direct, non-iterative method for recovering the complex wave in the exit-surface plane of a coherently illuminated object. The form of illumination is subject to certain conditions. By satisfying these conditions, the complex exit-surface wave is directly recovered from a single far-field intensity pattern, by solving a set of linear equations. These linear equations, whose coefficients depend on the incident illumination, are obtained by analyzing the autocorrelation function of the exit-surface wave. This autocorrelation is constructed by taking the inverse Fourier transform of the diffraction pattern. We introduce a preconditioning step, for the system of linear equations, which improves the robustness... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4139816 Sat, 23 Oct 2010 00:00:00 +0100 4139816 http://www.medworm.com/index.php?rid=4139817&cid=s_36217_166_f&fid=36217&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D21051145%26dopt%3DAbstract Authors: Zhang D, Grüner D, Oleynikov P, Wan W, Hovmöller S, Zou X A software-based method for collecting precession electron diffraction (PED) patterns is described. The PED patterns are obtained on a computer controlled transmission electron microscope. A series of electron diffraction (ED) patterns are collected as still ED frames at equal intervals, while the electron beam is precessed by one period (360°) around the optical axis. A PED pattern is obtained by combining the different ED frames, which resembles the sampling of a conventional PED pattern. Since intermediate ED frames are collected, it is possible to perform different post-processing strategies on the ED data. This can be used for geometric corrections to obtain accurate integrated intensities. The alignments and da... Ultramicroscopy journals http://www.medworm.com/rss/comments.php?id=4139817 Sat, 16 Oct 2010 00:00:00 +0100 4139817