Materials Literature
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Measurements of the back scatter coefficient as a function of incident electron energy, angle of incidence, and target atomic number are described. The results are compared with existing theories for normal and non-normal electron incidence. Analytical expressions for the back scatter coefficient, which can be used in…
DC conductivity and dielectric studies of CoxZn1−xFe2O4 (x = 0.32, 0.49, 0.79), BaFe12O19, and Mg0.25Zn0.75Fe2O4 are reported as a function of temperature and frequency. The lattice constant and the existence of a single phase are established from X-ray studies. The dielectric behaviour is attributed to the Maxwell-Wa…
Highly oriented surface layers of lithium disilicate crystals were grown by crystallizing glasses of composition Li2Si2O5 in a temperature gradient. The polar c axes of the crystallites were oriented parallel to the temperature gradient and perpendicular to the sample surface. The pyroelectric response of the glass-ce…
The electrical conductivity in tungsten phosphate glasses of three different compositions (67 mole% of W${\mathrm{O}}_{3}$-33 mole% ${\mathrm{P}}_{2}$${\mathrm{O}}_{5}$, 70 mole% M${\mathrm{O}}_{3}$-30 mole% ${\mathrm{P}}_{2}$${\mathrm{O}}_{5}$, and 81 mole% W${\mathrm{O}}_{3}$-19 mole% ${\mathrm{P}}_{2}$${\mathrm{O}}…
In this paper we consider energy transfer among impurity molecules in disordered systems. We use the result of Gochanour, Andersen, and Fayer [J. Chem. Phys. 70, 4254 (1979)] for the generalized diffusion coefficient D(t) in terms of the decay function Φ(t), in conjunction with separate calculations of Φ(t) in the pai…
The point dipole interaction model for molecular polarizability recently proposed by Applequist, Carl, and Fung is modified by replacing isotropic atomic point dipoles with anisotropic atomic point dipoles. The modified formalism, which is invariant to coordinate transformations, requires an additional empirical param…
Cross sections for Rayleigh and Mie scattering on a roughned conducting surface are given. The Rayleigh scattering is strongly enhanced by roughness. Rayleigh and Mie scattering are found to interfere with each other. The experimental consequences for surface enhanced Raman Scattering (SERS) are discussed. (AIP)
The pyrolysis of organic dianhydrides (e.g., 3,4,9,10-perylenetetracarboxylic dianhydride) in an evacuated system results in the loss of hydrogen, CO, and CO2 and the deposition of a chemically inert, metallic-appearing mirrolike film. The films are highly conducting (σRT250 Ω−1 cm−1) and can evidence either metallic…
A molecule adsorbed on the surface of a conducting prolate ellipsoid will Raman scAtter with an enhanced cross section. The relevance of this fact to the phenomenon of surface enhanced Raman scattering (SERS) is discussed. (AIP)
The newer tetracyclines are defined as those tetracyclines available in the United States but not approved for veterinary use. These include demeclocycline, methacycline, doxycycline, and minocycline. Of these, doxycycline and minocycline appear to offer advantages that would render them useful in certain situations i…
It is shown on the example of the dielectric data for Er-doped CaF 2 that very slight departures from the true Debye response can be assessed very accurately using the analysis of the real part of the susceptibility. Given adequate precision of measurements, this method is far more sensitive than the plotting of the c…
Chemically deposited PbS thin films have been prepared for use as infrared detectors. A systematic and elaborate study using scanning electron microscopy shows that the structure and crystallite size are related to the photosensitivity. Both the role of chemical oxidant influencing the type of conductivity and morphol…
For pt.I see ibid., vol.13, no.13, p.2485 (1980). The valence band of V 2 O 5 , calculated by means of a tight-binding method, is analysed in terms of projected densities of states on the different atomic orbitals, allowing a discussion of the bonding properties. The dispersion of the energy bands is discussed in conn…
A tight-binding method enabling the calculation of the energy bands of compounds with a complicated crystal structure such as V 2 O 5 is presented. It is based on certain assumptions and limitations concerning the choice of interactions which have to be taken into account. Perturbation theory is used in order to obtai…
Abstract The ESR-behaviour of antiferromagnetic and almost stoechiometric CrN is thoroughly investigated above its Neél-point. For polycrystalline samples a spectroscopic splitting factor g =1.965 and a differential line width ⊿B = 56,7 mT is measured at room temperature. All resonance lines exhibit Lorentzian charact…
A computational program, based on a diffusion surface deposition of oxygen, has been developed and applied to the calculation of a mesh-packed cold trap. The results were compared with experimental data for a forced-life test that was carried out by internal introduction of sodium peroxide into the sodium loop. Good a…
Fifty-six bales of medium staple cotton were spun into 40s yarn to evaluate spinning performance. In a parallel effort, roving samples from each bale were tested on a single-end drafting tester that duplicates the Tru-Set drafting system used in spinning. Front-zone drafting force and force-vari ability measurements w…
Abstract The rate of transformation from helical to all‐ trans ‐planar polytetrafluoroethylene (PTFE) at high pressures has been determined by monitoring the Raman spectra of PTFE following pressure jumps from the stability field of PTFE II to pressures between 9 and 14 kbar at temperatures between 0 and −30°C. The tr…
Abstract 1 H NMR spectra of polyisoprene were assigned using polymers of isoprene-1,1,4,4- d 4 , isoprene-1,1,5,5,5- d 5 , and isoprene-4,4- d 2 polymerized with various catalysts. The methylene-proton signal at 2.1 ppm in cis -1,4- and trans -1,4-polyisoprenes was divided into H 4 - and H 1 -proton signals; H 4 reson…
The immobilization of some medically useful enzymes were studied by means of radiation-induced polymerization at -78 degrees C. Glucose oxidase and glucose peroxidase were immobilized in the form of thin membranes inside polyvinyl chloride tubes and on polyethylene films; these membranes showed considerable activity y…