Materials Literature
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A three-dimensional analysis is given of the generation, diffusion, and collection of minority carriers injected by an electron beam in a semiconductor containing a p–n junction parallel to the surface. Using a modified Gaussian approximation to the three-dimensional electron beam dissipation function, analytical expr…
Two photoluminescence bands characterized by their excitation energy are observed in orpiment ($c\ensuremath{-}{\mathrm{As}}_{2}{\mathrm{S}}_{3}$). We assign the emission band with the peak energy of 1.53 eV to defect-related bound-exciton recombination. The luminescence band at 1.25 eV is induced by band-to-band exci…
A simple treatment of vibronic coupling in metalloporphyrins is described. Electronic degeneracy in the excited states is treated to arrive at simple expressions for the Raman excitation spectra and the absorption spectrum. The expressions are simple analogs of the usual A and B term expressions for the scattering ten…
In order to extend existing ideas on isotropic spin transfer mechanisms in bipyridine–metal complexes, a series of unsymmetrical methyl-substituted bipyridine ligands, and their nickel(II) and cobalt(II) complexes, have been prepared, and their 1 H nmr isotropic shifts measured experimentally. Simulating different ele…
ESR measurements are reported for Mn2 in kypton and xenon matrices at 4 °K.(AIP)
The oxo process consists of the reaction between an olefin, carbon monoxide, and hydrogen, in the presence of a catalyst (rhodium or cobalt) to form an aldehyde with one more carbon atom than the starting olefin. R-CH=CH 2 + CO + H 2 Catalyst/ R-CH 2 -CH 2 CHO The only exception is with the cobalt catalyst when the st…
We give two general integral expressions for the first and second derivatives of the so-called stick probability functions which are commonly used in analyzing x-ray-scattering results. Then it is shown that by letting the length of the stick go to zero, the limit of the second derivative can be expressed in terms of…
We have determined the Raman scattering cross section of pyridine molecules adsorbed on a "smooth" surface of silver prepared and characterized in an ultrahigh-vacuum chamber. The Raman intensity of the 1004-${\mathrm{cm}}^{\ensuremath{-}1}$ line of adsorbed pyridine was calibrated against the scattering intensity of…
A surface dielectric function of a semi-infinite plane-bounded metal is defined in the spirit of the plasmon-pole dielectric function of the bulk. It is modeled in such a way that the surface-plasmon dispersion relation is recovered for small momentum transfer. This function is employed to compute the image potential…
Infrared-reflectivity results on ${\mathrm{Cu}}_{3}$V${\mathrm{S}}_{4}$ and Raman scattering data as a function of temperature and hydrostatic pressure for ${\mathrm{Cu}}_{3}M{\mathrm{S}}_{4}$ (with $M=\mathrm{V},\phantom{\rule{0ex}{0ex}}\mathrm{N}\mathrm{b},\phantom{\rule{0ex}{0ex}}\mathrm{T}\mathrm{a}$) are reported…
A metal-insulator transition was found by Aubry in a one-dimensional tight-binding model containing a modulation potential incommensurate with the crystal lattice. In this article the extended bandlike states that occur in the metallic regime are studied using a quasiclassical approach. Near the metal-insulator transi…
Raman scattering and x-ray diffraction measurements are used to correlate finite-size effects on the Raman spectra of nonpolar vibrational modes in BN. The BN microcrystalline samples used exhibited domain sizes varying from 4.4 to 78.5 nm in the plane and 1.5 and 47.5 nm perpendicular to the planes. The Raman measure…
An unstretched alpha -form specimen of polarised PVDF shows four TSC peaks designated P 1 , P 2 , P 3 and P 4 in ascending order of temperature. The P 1 and P 2 peaks are associated with the dipolar depolarisation due to the alpha a and alpha e relaxations, respectively. The P 3 and P 4 peaks may both be attributed to…
Abstract Transition metal complexes often have low‐lying excited electronic states and, as a consequence, tend to be electronically labile, i.e. , their electronic properties exhibit pronounced sensitivity to external perturbations. Often drastic changes in various spectroscopic properties indicating substantial elect…
The high resolution infrared luminescence spectra of ReCl6 2- in K2PtCl6 and of ReBr6 2- in Cs2ZrBr6 have been measured between 10 000 cm-1 and 3000 cm-1 at liquid helium temperatures. Comparison with the luminescence spectra in the visible region has enabled nine luminescence transitions to be observed in the bromide…
Non-empirical calculations of the electronic structure of NiO and related compounds have proven to be problematic, in that NiO is an insulator both above and below the antiferromagnetic ordering temperature (TN approximately 525K) with a gap of approximately 4 eV. This is so despite the partly filled d-band on the Ni…
The (220) lattice plane spacing of an almost perfect crystal of silicon was measured by means of a combined scanning ($\mathrm{LLL}$) x-ray interferometer and a two-beam optical interferometer. From 170 measurements, a value ${d}_{220}=(192015.560\ifmmode\pm\else\textpm\fi{}0.012)$ fm results in vacuum at 22.50\ifmmod…
A differential anomalous x-ray scattering technique has been developed for structural studies of disordered and amorphous systems. The results on amorphous Ge${\mathrm{Se}}_{2}$ are consistent with the twofold coordination of Se and the fourfold coordination of Ge. The results on amorphous GeSe are consistent with thr…
Abstract The microstructure of melt-crystallized linear polyethylene has been correlated with the variables of crystallization for most readily attainable conditions. All samples are filled with well defined lamellae with an average chain inclination of about 35° to lamellar normals. The lamellar thickness depends up…
Abstract The lamellar microstructure of a wide range of melt-crystallized polyethylenes has been examined in the context of spherulitic organization. Radial continuity is achieved through lamellar continuity. In the simplest cases ridged or planar sheets grow outwards along b, maintaining their identities over distan…