Topic
Mean free path
About: Mean free path is a research topic. Over the lifetime, 4412 publications have been published within this topic receiving 114418 citations.
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TL;DR: In this article, the shape of the self-preserving spectrum depends on the value of the parameter A = 1.5 μGφ/πkTN, where μ is the fluid viscosity, k Boltzmann's constant, and T the absolute temperature.
94 citations
TL;DR: In this article, the thermal conductivity of crystalline GaAs is calculated using first-principles lattice dynamics and the harmonic and cubic force constants are obtained by fitting them to the force-displacement data from density functional theory calculations.
Abstract: In this paper, thermal conductivity of crystalline GaAs is calculated using first-principles lattice dynamics. The harmonic and cubic force constants are obtained by fitting them to the force-displacement data from density functional theory calculations. Phonon dispersion is calculated from a dynamical matrix constructed using the harmonic force constants and phonon relaxation times are calculated using Fermi's Golden rule. The calculated GaAs thermal conductivity agrees well with experimental data. Thermal conductivity accumulations as a function of the phonon mean free path and as a function of the wavelength are obtained. Our results predict a significant size effect on the GaAs thermal conductivity in the nanoscale. Relaxation times of optical phonons and their contributions from different scattering channels are also studied. Such information will help the understanding of hot phonon effects in GaAs-based devices.
93 citations
TL;DR: In this article, a simple model is developed which describes the reduction of the mean free path of conduction electrons in metals near a grain boundary, which leads to a decrease of the self-energy of flux lines in a layer which is considerably thicker than the perturbed zone of the boundary itself.
Abstract: A simple model is developed which describes the reduction of the mean free path of conduction electrons in metals near a grain boundary. This leads to a decrease of the self-energy of flux lines in a layer which is considerably thicker than the perturbed zone of the boundary itself. The model yields pinning forces which agree, within an order of magnitude, with recent measurements on niobium bicrystals, and with observed values of grain boundary pinning in Nb/sub 3/Sn.
93 citations
TL;DR: In this article, a simple universal equation for the computation of attenuation lengths (L) for any material, necessary for quantifying layer thicknesses in XPS, is presented.
Abstract: An analysis is presented for a simple, universal equation for the computation of attenuation lengths (L) for any material, necessary for quantifying layer thicknesses in XPS. Attenuation lengths for selected materials may be computed from the inelastic mean free path (lOpt) computed, in turn, from optical data. The computation of L involves the transport mean free path and gives good L values where values of lOpt are available. However, lOpt values are not available for all materials. Instead, l may be calculated from the TPP 2M relation, but this requires the accurate estimation of a number of materials parameters that vary over a wide range. Although these procedures are all soundly based, they are impractical in many analytical situations. L is therefore simply re-expressed, here, in terms of the average Z of the layer (from XPS analysis), the average atomic size, a (varies in a small range) and the kinetic energy E of the emitted electron. A new equation, "S3", is established with an RMS deviation of 8% compared with the values of attenuation length calculated from lOpt available for elements, inorganic compounds and organic compounds. This excellent result is suitable for practical analysis. In many films, an average value of a of 0.25 nm is appropriate and then L may be expressed only in terms of the average Z and E. Then, L expressed in monolayers, equation "S4", exhibits an RMS deviation of 9% for many elements. These results are valid for the energy range 100 to 30000 eV and for angles of emission up to 65o.
93 citations
TL;DR: In this paper, the thickness dependence of the conductivity of copper, aluminium, silver, gold, nickel and platinum films was measured with high accuracy for various conditions of the evaporation.
92 citations