Materials Literature
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The bonding at the interface between calcium fluoride and the silicon (111) surface has been studied with surface-sensitive core-level photoemission spectroscopy. The interface is found to consist of predominately Si---Ca bonds, with a dissociation of the ${\mathrm{CaF}}_{2}$ molecule at the interface resulting in dep…
Specific heat capacities of “superionic conductor”, Ag chalcogenides have been measured for Ag 2 S, Ag 2 Se and Ag 2 Te in the temperature range, 120–520 K. In every case, the heat capacity at constant pressure, C p decreases with increasing temperature over the fairly wide range above transition temperature. The beha…
Triplet decay of Mg and Zn phthalocyanins have been studied by laser flash photolysis as a function of concentration. The triplet decay mechanism changes from a near first order in dilute solution to an almost second order in concentrated solutions. This is interpreted in terms of triplet–triplet recombinaison. With t…
The Raman spectrum of the uncoupled O–H and O–D stretching vibrations of HDO dissolved in H2O high-density amorphous ice, that was made from ice Ih, has been measured at 12 K for the sample as recovered at 77 K and after heating it at 5 K min−1 from 12 K to, successively, 80, 90, 100, ..., 170 K and annealing there fo…
Variations in the structural energy of solid carbon along a transformation path from a graphitic structure with . . .[AA] . . . stacking to hexagonal diamond are calculated using the first-principles pseudopotential local-orbital total-energy method. The transformation path is that defined in an earlier study of the t…
An ab initio pseudopotential method is used to study the structural properties of SiC at low and high pressures. For cubic SiC, the calculated ground-state properties, such as the equilibrium lattice constant, bulk modulus, and cohesive energy, are in good agreement with experiment. The indirect band gap of cubic SiC…
The oxygen vacancy in \ensuremath{\alpha}-quartz has been studied in various charge states using the molecular-orbital techniques modified intermediate neglect of differential overlap (MINDO/3) and its open-shell version (MOPN). The solid containing the defect is simulated by a cluster of 30 to 40 atoms, including hyd…
A new algorithm for the construction of a dense random packing of a binary mixture of hard spheres is presented. The algorithm uses periodic boundary conditions and is capable of handling any binary composition with radius ratio between 1.0 and 2.0. Computed results are relatively insensitive to variations in program…
We present a first-principles approach to deriving the relative energies of valence and conduction bands at semiconductor interfaces, along with a model which permits a simple interpretation of these band offsets. Self-consistent density-functional calculations, using ab initio nonlocal pseudopotentials, allow us to d…
Pure metals were used to prepare Cu(S) and Ag(S) solid solutions at high temperatures; resistivity was measured at 4.2 K. The effects of possible contamination and evolution of the alloys during cooling were examined. the intrinsic resistivities of S in Cu (8.7+or-0.1 mu Omega cm per at%) and in Ag (8.9+or-0.9 mu Omeg…
The authors have investigated the contact charging of polymers by metals, paying particular attention to the variation of charge transfer from place to place on the sample surface, and from one sample to another. For most polymers they find that charge transfer is unaffected by attempts at purification and is much the…
Amino acid sequence studies show that the aliphatic amidase (EC 3.5.1.4) from Pseudomonas aeruginosa PAC142 consists of a single polypeptide chain of 346 residues, giving an Mr of 38,400. The evidence from the amino acid studies is in complete agreement with that deduced from the DNA sequence of the amiE gene. Studies…
The decay of GR1 cathodoluminescence associated with the neutral vacancy in diamond has been studied in the temperature range 10 to 77 K. Exponential decay of the luminescence is only obtained when short (5 ns) widely spaced (10 mu s) pulses are used, yielding a decay time of 3.1 ns in the temperature range studied. I…
Abstract Cellulose linters with starting degrees of polymerization between 100 < DP n < 6000 had been hydrolytically degraded (0.5 M aqueous solution of KHSO 4 , degradation temperature 40°C and 60°C) and the results compared with those obtained in a former study on pure cotton cellulose using the same degradati…
Translational invariance requires that the electron density operator is not diagonal in a Wannier representation. We show that this leads to important terms in the electron-electron interaction Hamiltonian, terms which involve the bond-charge density and which are not included in the widely studied extended Hubbard mo…
We present a new scheme to study the linear response of crystals which combines the advantages of the dielectric-matrix and supercell (``direct'') approaches yet avoids many of their drawbacks. The numerical complexity of the algorithm is of the same order as that of a self-consistent calculation for the unperturbed s…
The vibrational IR spectra of a CsBi(MoO4)2 crystal have been studied in the temperature range 16−300° K in polarized radiation (E‖b, E‖c) in the frequency range 600−1000 cm−1. The influence of structural phase transitions (Tc1 = 135° K, Tc2 = 330° K) on the IR reflection spectra of CsBi(MoO4)2 has been found. By comp…
Abstract In a continuation of previous work (1), the melting and crystallization behavior of the layered oxidized skin on thermally oxidized inner wall surfaces of different high density polyethylene (HDPE) pipes was studied. By hot stage polarized light microscopy on 5 μm thick cross‐sections of the skin, melting was…
The amplitude equation for thermal convective nematic liquid crystals is derived from the equations of motion. The appearance of various patterns (normal rolls, undulations, zigzags, etc.) in different parameter regimes is described in a unified manner. The effect of a horizontal magnetic field is included and the cor…
An improvement of the classical theory of extinction in mosaic crystals is made by starting from the energy transfer equations valid for a general-type crystal according to Zachariasen's [Acta Cryst. (1967), 23, 558-564] classification. Within the assumption that only the integrated intensity of the diffraction peak i…