Materials Literature
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An approximate relativistic treatment of the differential cross section for Compton scattering against bound electron states is discussed. A simple relationship between the cross section and the Compton profile is found. On contrast to previous work this relationship is valid for all scattering angles.
The very-low-frequency Raman scattering from vitreous silica was measured for frequency shifts $\ensuremath{\omega}$ as small as 4 ${\mathrm{cm}}^{\ensuremath{-}1}$. The data were compared with present theories on disorder-induced sacttering; for $\ensuremath{\omega}<20$ ${\mathrm{cm}}^{\ensuremath{-}1}$ an excess…
A new method for measuring absolute electron-impact differential cross sections (DCS) for elastic scattering in gases is described. The technique uses a well-defined crossed-beam scattering geometry in which the relative target densities of an unknown and a secondary standard gas are accurately determined by a calibra…
Magnetic-susceptibility and EPR measurements are reported which provide the first unambiguous evidence for a spin-Peierls transition in a system of linear one-dimensional antiferromagnetic Heisenberg chains. The material studied is TTFCu${\mathrm{S}}_{4}$${\mathrm{C}}_{4}$${(\mathrm{C}{\mathrm{F}}_{3})}_{4}$ (TFF stan…
We have used the technique of static field induced second harmonic generation in liquids to determine the second order hyperpolarizability β, and the third order hyperpolarizability γ, for a wide range of conjugated and nonconjugated organic molecules. The adequacy of the Onsager local field formulation was tested as…
The Raman spectra of some binary alkali silicate glasses and crystals have been measured and the results interpreted. The glasses are of composition M2O⋅xSiO2, 1⩽x⩽4 and M = Li, Na, K. There is a strong resemblance between glassy and crystalline spectra which is consistent with a considerable amount of structural diso…
The energy distributions of electrons transmitted through thin free films of Be, Al and Ge with initial energies of E 0 =0.5-4.0 keV have been investigated with a spherical retarding-field analyser. The most probable (E m /E 0 ) and mean (E/E 0 ) energies as a function of the penetration depth x depend on the Z of the…
Liquid-crystal twisted nematic structures can be made with twist angles other than the conventional 90 degrees . It is shown that theoretically the transmission of such a structure when placed between two polarizers aligned parallel and perpendicular to the respective surface molecular directors is given by T=(1+u 2 )…
Logarithmic anomalies in the temperature-dependent resistivity of a series of amorphous alloys have been measured and shown to be nonmagnetic in origin. We associate these anomalies with the noncrystalline structure.
Electron energy loss measurements have been made up to 40 eV on specimens of several members of the mica group and quartz. By means of a Kramers-Kronig analysis the dielectric functions epsilon 1 and epsilon 2 have been deduced from the energy loss function. The excitations observed in mica and quartz are discussed wi…
The magnetostriction of a uniaxial MnF2 antiferromagnet is measured at 10°K in a field up to 150 kOe. A jump in the deformation along the axis of crystal symmetry and subsequent quadratic growth are observed in a magnetic field (Hc = 91.7 kOe) parallel to this axis. The deformation grows quadratically in H in a perpen…
With the realization that nuclear energy had a vast potential for peacetime development, universities throughout the country began to develop courses in nuclear energy. A pioneering educational effort was necessary because there were an inadequate number of trained faculty, no established curricula, no textbooks, and…
Article Coalescence Times of Single Water Drops at Oil/Water Interfaces: Effect of Interface Age Interface Extent and Drop Size was published on September 1, 1975 in the journal Tenside Surfactants Detergents (volume 12, issue 5).
The major families of ternary compounds and their structures are reviewed, followed by a discussion of synthesis and crystal growth methods for ternary chalcogenides. Finally, a survey is given on a variety of recently synthesized multi-cation chalcogenides and some of their properties.
Summary An electron-probe microanalysis of tetrahedrite occurring together with the latest-deposited pyrite-cinnabar association in the Chiprovtsi lead-silver deposit yielded more than 16 wt. % Ag and more than 18 wt. % Hg. X-ray powder examination established an extremely large unit-cell edge, a 10.64±0.01 Å. Vickers…
Simple mechanisms are proposed for both NO decomposition and NO2 formation at typical combustion conditions. Analytical studies indicate that the fast NO2 reactions, NO2 + M NO + O + M and NO + O2 O + N2, have a strong effect on both systems. During NO decomposition (1400 < T < 2500°K), these reactions maintain equili…
In the large family of ternary compounds one could expect to find systematic trends for the various physical properties. For instance the geometrical arrangement of the atoms is, in most ternaries, tetrahedral. Beyond qualitative laws very few quantitative relationships have been established between cristallographic s…
Abstract Ammoxidation of acrolein (Al) on Fe 2 O 3 ‐Bi 2 O 3 ‐P 2 O 5 (44.5:44.5:11.0 mol%) catalyst was studied in a fixed bed reactor. The main products were acrylonitrile (AN), CO 2 and acetonitrile; and CO was negligibly small. The rate equations for Al conversion and product formation, together with their apparen…
Abstract The values of the vitreous transition temperature, T g , of three poly(methacrylic ester)s having bulky side groups are correlated with structural effects. T g has been obtained experimentally by means of differential calorimetry and by the tensiometric method suggested by Ferroni . The experimental values of…
Using ENDOR we have characterized the 23Na and 1H hyperfine structure of the CO2− radical ion in sodium formate single crystals. In contrast to previous studies we have detected CO2− in uv irradiated samples. ENDOR studies of the 23Na hfs together with CNDO calculations indicate that the CO2− forms a tight ion pair wi…