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Photon Statistics in Single Molecule ExperimentsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Single molecule fluorescence experiments yield a stream of photocounts, whose statistical properties contain valuable information about processes within the molecule and in its microscopic environment. The photon statistics display features specific of single quantum systems and are therefore best discussed in the frame of a quantum mechanical theory of radiation. The present summary of a lecture given in April 2002 at the Hofgeismar Spring School on single molecules presents the main concepts used in quantum theory of light, together with a few useful references, and discusses some illustrations and applications to single...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Michel Orrit Source Type: journals

Single Protein Molecules Visualized and Tracked in the Interior of Eukaryotic CellsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the last few years the visualization and tracking of single fluorescent proteins, nanometer-sized RNP particles and viruses within the cellular interior was accomplished. This became feasible by use of photostable fluorescent dyes, extremely low probe concentrations, and wide-field fluorescence microscopic setups equipped with sensitive slow-scan or intensified CCD cameras. This paper reviews the results of the studies performed so far, discusses potential problems and gives an outlook on future applications.
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Ulrich Kubitscheck Source Type: journals

DNA-based Molecular NanotechnologyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The use of molecular building blocks opens a new dimension for nanotechnology. Biomolecules offer a variety of possibilities for manipulation, provide a new size dimension and are especially suitable for "bottom up" approaches. Nucleic acids are of special interest due to their ability of self-organization, the achieved combinatorial information capacity and its molecular-biological processability. Here we present an approach for a molecular component systems with DNA-based elements and products that is suitable for molecular nanotechnology. Oligonucleotides thereby serve as biological modifiers of nanoparticles and surfac...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Andrea Csáki, Gunter Maubach, Detlef Born, Jörg Reichert, Wolfgang Fritzsche Source Type: journals

On the Field Enhancement at Laser-illuminated Scanning Probe TipsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
First results of a new dynamic approach to calculate the field enhancement at a metal ellipsoid close to a metal surface are presented. The theoretical approach is based on the solution of Maxwells equations. The numerical calculation is influenced by the dielectric constants of both metals, the angle of incidence of the monochromatic electromagnetic wave, the distance of the ellipsoid to the metal surface and the semi axis ratio of the ellipsoid.
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Stefan Klein, Tobias Witting, Klaus Dickmann, Pavel Geshev, Michael Hietschold Source Type: journals

Surface-enhanced and STM-tip-enhanced Raman Spectroscopy at Metal SurfacesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The strong electromagnetic field enhancement, occurring at illuminated metal structures with sub-wavelength dimensions, is exploited to develop Raman spectroscopy with exceedingly high sensitivity and lateral resolution, possibly down to single molecule detection. After reviewing Surface Enhanced Raman Spectroscopy (SERS) on single crystalline surfaces and colloids we present recent results on the Tip Enhanced Raman Spectroscopy (TERS) approach, where a metal tip is used as an external enhancing unit. In this way the electromagnetic and chemical surface enhancement are physically separated: the former is confined to the ti...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Bruno Pettinger, Gennaro Picardi, Rolf Schuster, Gerhard Ertl Source Type: journals

STM Investigation on Single, Physisorbed DendrimersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Porphyrin dendrimers were synthesized to mimic naturally occurring proteins, which catalyze a number of biochemically important reactions. In addition, chiral dendrimers were prepared as model compounds for the study of nanoscopic chirality. The structures of these dendrimers cannot be characterized by x-ray, as most dendrimers do not crystallize. We succeeded to image single, physisorbed dendrimers on noble metal surfaces with STM. All examined dendrimers can easily be (re)moved with the STM tip, even at low scanning currents (low pA range). One possibility to avoid this, is to change the peripheral groups of the dendrime...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: L. Merz, J. Hitz, U. Hubler, P. Weyermann, F. Diederich, P. Murer, D. Seebach, I. Widmer, M. Stöhr, H.-J. Güntherodt, B. A. Hermann Source Type: journals

The Imaging of Small Domains of J-Aggregated Dye Molecules by Scanning Near-Field Optical MicroscopyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The concept of high resolution imaging of a sample on a metal substrate by scanning near field optical microscopy (SNOM) with the tetrahedral tip is used for imaging of domains of oriented dye molecules on a metal substrate at a resolution in the order of 10 nm. The metal substrate is important for obtaining a high resolution in the SNOM images and at the same time it is expected to provide a mechanism for an increased contrast in SNOM imaging by scanning probe enhanced elastic scattering of molecules in the gap between a metal tip and a metal surface.
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Jörg Heimel, Harald Fuchs, Ulrich C. Fischer Source Type: journals

Theory of Near-field Optical Imaging with a Single Molecule as Light SourceEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Scanning near-field optical microscopes (SNOM) illuminate a sample in the very near-field using a nanometer sized tip. Ideally, the light source should be point-like and many efforts have been made to optimize tip efficiency (see, for example, the article of Heimel et al in this issue). Very recently, Sandoghdar et al have realized a molecular probe tip in which a terrylene molecule inserted in a paraterphenyl microcrystal is attached at the extremity of the probe tip [1]. The excited molecule behaves as a point-like light source which is raster scanned over an aluminium patterned structure. We propose here an analysis of ...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Gérard Colas des Francs, Christian Girard, Alain Dereux Source Type: journals

Plug Harvesting by Atomic Force MicroscopyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, AFM not only allows imaging of structures in the submicrometer range, it may also be used to manipulate them. By applying forces to the AFM tip approximately 10 fold higher than those used for imaging we were able to dislocate plugs from NPCs (see figures). The macromolecules sticking to the AFM tip can be used as substrates for further experiments, for example RT-PCR protocols.
Source: Single Molecules - October 4, 2006 Category: Physics Authors: L. Albermann, C. Schäfer, V. Shahin, J. Reinhardt, H. Oberleithner Source Type: journals

Influence of Monovalent Salt on the Molecular Structure of Single DNA Complexes with Positively Charged Dendronized PolymersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In cells and viruses as well as non-viral gene delivery systems, DNA is complexed with different molecules to form highly condensed structures. A wide range of conditions that cause DNA to collapse into compact structures has been discovered [1]. However, in most of these cases an exact description of these structures cannot be given. Since the complex stability is largely due to electrostatic forces, it can be modulated by varying the salt concentration. Apart from the biological aspects the study of the molecular structure of polyelectrolyte complexes may be used to improve our general understanding of polyelectrolyte in...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Illdiko Gössl, Lijin Shu, Dieter Schlüter, Jürgen P. Rabe Source Type: journals

Non-exponential Kinetics of Photoblinking and Photobleaching of Rhodamine 6G in PolyvinylalcoholEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Photobleaching and photoblinking have proven to be the main bottleneck for single-molecule microscopy and spectroscopy at room temperature. Here, a quantitative ensemble study of the kinetics of photoblinking and photobleaching at room temperature of a typical fluorescent label, Rhodamine 6G, in a polar, hydrogen bonding, solid matrix of polyvinylalcohol is presented as a function of the excitation intensity and the presence of oxygen. To achieve uniform irradiation of all molecules present in the excitation focus, the sample (2.0 x 10-5 M R6G in PVA spin-coated on a quartz substrate) is covered by a pinhole array mask wit...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: R. Zondervan, F. Kulzer, G. Mathies, M. Orrit Source Type: journals

Individual LH3 (B800-820) Light-Harvesting Complexes Studied by Optical Single-Molecule SpectroscopyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The initial event in bacterial photosynthesis is the absorption of sunlight by an array of pigment-protein complexes, the so called light-harvesting complexes (LH). The absorbed light energy is then efficiently transferred to the reaction centre (RC), where the charge separation and thus the primary conversion into chemical energy takes place. The photosynthetic purple bacterium Rhodopseudomonas (Rps.) acidophila usually contains two types of light-harvesting complexes, light-harvesting complex 1 (LH1) and light-harvesting complex 2 (LH2). When grown under low-light and/or low temperature conditions, an additional spectros...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: S. Oellerich, M. Ketelaars, J.-M. Segura, G. Margis, W. de Ruijter, J. Köhler, J. Schmidt, T.J. Aartsma Source Type: journals

Inelastic Effects in Molecular ConductorsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this work we present a framework for the calculation of the conduction properties of a metal-molecule-metal junction which is in contact with its thermal environment. The effects of thermal relaxation and dephasing on the transmission properties of the junction were studied using a simple tight binding model for the molecular conductor. The interaction between the molecular system and the thermal environment is described on the level of the Redfield theory, which is a weak electron-phonon coupling scheme, modified for the description of steady-state situations. We show that the transmitted flux consists of two (generall...
Source: Single Molecules - October 4, 2006 Category: Physics Authors: Dvira Segal, Abraham Nitzan Source Type: journals

Book Review: Photonics of Biopolymers. By N.L. VekshinEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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Source: Single Molecules - October 4, 2006 Category: Physics Authors: K. O. Greulich Source Type: journals

Single Photons Interfere, even if they are Generated IndependentlyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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Source: Single Molecules - October 4, 2006 Category: Physics Authors: K.O. Greulich Source Type: journals

Photostability Data for Fluorescent Dyes: An Update.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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Source: Single Molecules - October 4, 2006 Category: Physics Authors: Thomas Schmidt, Ulrich Kubitscheck, Daniel Rohler, Uli Nienhaus Source Type: journals

Job Offers: Single Mol. 5-6/2002Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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Source: Single Molecules - October 4, 2006 Category: Physics Source Type: journals

Conference Announcements: Single Mol. 5-6/2002Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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Source: Single Molecules - October 4, 2006 Category: Physics Source Type: journals

Editorial: Spring School on Physics, Chemistry and Biology with Single Molecules, Hofgeismar, April 4th to 8th 2002Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
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Source: Single Molecules - November 1, 2002 Category: Physics Authors: Ulrich Kubitscheck, Urlich Fischer Source Type: journals