MedWorm: Physics

Acousto-optic wavefront sensing and reconstruction

Applied Optics — Thu, 01 Jan 2009 05:00:00 +0100

We employ an acousto-optic cell as a tunable-pitch wavefront sensor and study its performance. The index of refraction of two cross-standing waves forms, in the near field, an adjustable array of caustics. These caustics, similar to the lenslets used for Hartmann-Shack sensing, were measured to ... (Source: Applied Optics)

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Nonlinear switching and reshaping of slow-light pulses in bragg-grating couplers

Journal of the Optical Society of America B — Mon, 01 Dec 2008 05:00:00 +0100

We study the propagation and switching of slow-light pulses in nonlinear directional couplers composed of two parallel waveguides, where each waveguide contains a Bragg grating. We show that by optimizing the phase shift between the Bragg gratings, one can obtain specific dispersion characteristics ... (Source: Journal of the Optical Society of America B)

Visually discerning the curvature of the earth

Applied Optics — Mon, 01 Dec 2008 05:00:00 +0100

Reports and photographs claiming that visual observers can detect the curvature of the Earth from high mountains or high-flying commercial aircraft are investigated. Visual daytime observations show that the minimum altitude at which curvature of the horizon can be detected is at or slightly below ... (Source: Applied Optics)

Noncircular glories and their relationship to cloud droplet size

Applied Optics — Mon, 01 Dec 2008 05:00:00 +0100

The atmospheric glory caused by backscattering of sunlight from clouds usually has circular colored rings. However, glories with noncircular rings are frequently observed, especially along the edges of clouds. Noting that the angular radius of the rings of glories is a sensitive indicator of the ... (Source: Applied Optics)

Intracavity harmonic generation in figure-8 undulator free electron lasers

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

G. Dattoli, P. L. Ottaviani, and S. Pagnutti We consider a free electron laser oscillator employing an exotic undulator provided by a figure-8, a device having the orthogonal field component oscillating with a period one-half of the radial component. The harmonic spectrum of such an oscillator device is fairly reach. We have indeed emission on ... [J. Appl. Phys. 104, 073114 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

Aligned single-walled carbon nanotubes by langmuir--blodgett technique

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

Lu Jia, Yafei Zhang, Jinyong Li, Chang You, and Erqing Xie Single-walled carbon nanotubes (SWNTs) were chemically functionalized with amphiphilic octadecylamine after purification. Lower density and highly oriented SWNTs were obtained via LangmuirBlodgett (LB) technique. A model was introduced to explain the compression-induced alignment. The phase behavior ... [J. Appl. Phys. 104, 074318 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

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Operating lifetime recovery in organic light-emitting diodes having an azaaromatic hole-blocking/electron-transporting layer

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

Viktor V. Jarikov, Kevin P. Klubek, Liang-Sheng Liao, and Christopher T. Brown Azaaromatic compounds (AACs) are widely used in organic light-emitting diodes (OLEDs), especially as efficient electron transporters. Yet, the operating lifetime of OLEDs is always compromised when AACs are involved in anything more than electron transport (e.g., hole blocking). We show (i) the oper ... [J. Appl. Phys. 104, 074914 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

The vacancy in silicon: a critical evaluation of experimental and theoretical results

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

Hartmut Bracht and Alexander Chroneos Recent experimental studies of Shimizu et al. [Phys. Rev. Lett. 98, 095901 (2007)] revealed an activation enthalpy of 3.6 eV for the vacancy contribution to Si self-diffusion. Although this value seems to be in accurate agreement with recent theoretical results, it is at variance with experiments on ... [J. Appl. Phys. 104, 076108 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

Structural properties of nitrogenated amorphous carbon films: influence of deposition temperature and radiofrequency discharge power

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

G. Lazar, B. Bouchet-Fabre, K. Zellama, M. Clin, D. Ballutaud et al. The structural properties of nitrogenated amorphous carbon deposited by radiofrequency magnetron sputtering of graphite in pure N plasma are investigated as a function of the substrate temperature and radiofrequency discharge power. The film composition is derived from x-ray photoemission spectrosco ... [J. Appl. Phys. 104, 073534 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

Response spectrum of coupled nanomechanical resonators

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

J. Dorignac, A. Gaidarzhy, and P. Mohanty We develop a simple continuum model to analyze the vibrational modes of a nanomechanical multielement structure. In this model, arrays of submicron cantilevers located symmetrically on both sides of the central clamped-clamped nanobeam are replaced by a continuum. In this approach, the equations of ... [J. Appl. Phys. 104, 073532 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

Enhanced ferroelectric properties of hf-doped bismuth titanate thin films on sto (111) substrates

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

X. P. Wang, J. Zhu, W. B. Luo, Y. Zhang, and Y. R. Li BiTiO (BIT) and Hf-doped BIT (BTH) thin films have been fabricated on (111) SrTiO substrates with SrRuO bottom electrodes by pulsed laser deposition, respectively. X-ray photoelectron spectroscopy investigation revealed that Hf doping would strengthen the oxygen covalent bond to B-site ions, which c ... [J. Appl. Phys. 104, 074112 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

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Electron dephasing scattering rate in two-dimensional gaas/ingaas heterostructures with embedded inas quantum dots

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

I. R. Pagnossin, A. K. Meikap, A. A. Quivy, and G. M. Gusev We report a comprehensive study of weak-localization and electron-electron interaction effects in a GaAs/InGaAs two-dimensional electron system with nearby InAs quantum dots, using measurements of the electrical conductivity with and without magnetic field. Although both the effects introduce temper ... [J. Appl. Phys. 104, 073723 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

Forced chemical mixing in model immiscible systems under plastic deformation

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

Francesco Delogu Molecular dynamics has been employed to investigate forced chemical mixing in binary immiscible systems induced by plastic deformation. Four X matrix-Y precipitate model systems with thermodynamic and structural features almost identical to the ones of AgCu solid solutions but different mechanical p ... [J. Appl. Phys. 104, 073533 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

Detection of magnetic nanoparticle fusion by magnetic measurements

Journal of Applied Physics — Sat, 11 Oct 2008 18:39:27 +0100

Marko JagodiC, Saso Gyergyek, Zvonko JagliCic, Darko Makovec, and Zvonko Trontelj A ferrofluid composed of gamma-FeO nanoparticles of an average diameter of 11 nm dispersed in n-decane was prepared. A series of magnetic measurements was carried out on samples frozen in a magnetic field and in zero magnetic field. The influence of interparticle interactions on the magnetic behavio ... [J. Appl. Phys. 104, 074319 (2008)] published Fri Oct 10, 2008. (Source: Journal of Applied Physics)

Terahertz heterodyne receiver with quantum cascade laser and hot electron bolometer mixer in a pulse tube cooler