Materials Literature
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X-ray photoelectron spectra (XPS) of the valence bands of crystalline and amorphous As, Sb, and Bi have been measured. The results are compared with band-structure calculations for the crystalline materials. A splitting, $\ensuremath{\Delta}E$, of the "$s$-like" peak for the crystalline phase disappears in the amorpho…
The reaction kinetics of U + 3/2 H2⇄UH3 was studied with fine powders on an ultrahigh-vacuum microbalance. The kinetics were found to be first order with respect to uranium for the hydriding reaction and nearly zero order with respect to uranium hydride for dehydriding. A new reaction mechanism is proposed to account…
The polarized Stokes and anti-Stokes Raman spectrum of amorphous ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$ has been measured at several temperatures in the range 20-448 \ifmmode^\circ\else\textdegree\fi{}K with a He-Ne laser, and at room temperature with a c.w. dye laser. Using the Shuker-Gammon data-reduction method, the…
The principle of a new electrochromic display based on an oxidation-reduction reaction of an organic compound of the viologen family is described. The result is a display having a built-in memory, high contrast, a low switching voltage, and a low mean power consumption.
The resonance aspect of chemical bonding is extended to solids with particular emphasis on its consequences for structural and vibrational properties. It is shown, for example, that the square of the infrared effective charge is proportional to the high-frequency dielectric constant in resonance-bonded systems. The IV…
Measurements of the magnetic susceptibility, magnetic moment and specific heat of holmium phosphate, HoPO 4 , show that there is a magnetic phase transition to an antiferromagnetic state at a Neel temperature of 1.39 K. The measurements indicate that the g value of the Ho 3+ ion is highly anisotropic with g c =16.0, g…
Surface-state transitions on ordered silicon (100)2\ifmmode\times\else\texttimes\fi{}1 and (111)7\ifmmode\times\else\texttimes\fi{}7 surfaces have been observed by electron energy-loss spectroscopy. The surface transitions were identified by comparing the clean ordered surfaces with clean disordered surfaces, and with…
A computer study of a tetrahedrally coordinated random-network structure is reported as a model for amorphous Si or Ge. A previous model is refined to produce equal near-neighbor distances; it is more carefully statistically characterized and the coordinates of each individual atom are now known. The radial distributi…
EPR investigations of ${\mathrm{Ag}}^{2+}$ in the series of isomorphous hosts SrO, CaO, and MgO show that the low-temperature Jahn-Teller effect is static for SrO: ${\mathrm{Ag}}^{2+}$, predominantly static but intermediate to the dynamic effect for CaO: ${\mathrm{Ag}}^{2+}$, and predominantly dynamic but slightly int…
Abstract A modified Eyring rate expression based on an asymmetrical potential energy barrier is used to predict the onset of plastic yield in glassy polymers. Equations for the prediction of plastic yield delay times in creep and yield stresses in constant rate of strain testing are developed and compared to experimen…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry and biology of vitamin B6. 32. Selective modification of the .alpha.4 position of pyridoxol. 4-Vinyl analog of pyridoxal, a potent antagonist of vitamin B6W. Korytnyk, G. B. Grindey, and B. LachmannCite this: J. Med. Chem. 1973, 16, 7, 865–867Publication Date (Prin…
Sodium diarsenate at room temperature is monoclinic with lattice parameters a = 5.969(1), b = 10.126(1), c = 12.272(3) Å and β = 92.87(2)°. There are four formula units per cell with space group C2/c. The structure was refined by full-matrix least-squares to a final R value of 0.027 utilizing 1157 reflections measured…
In this second contribution the Fraunhofer diffraction patterns from apertures of the form of an equilateral triangle, a square, a regular pentagon, a hexagon and an octagon are compared with the calculated maps of the intensity distribution. For each shape of the aperture the first few maxima and minima of the intens…
(1973). Atomizing molten metals — a review. Canadian Metallurgical Quarterly: Vol. 12, No. 3, pp. 309-322.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReaction of phenyl isocyanate with N-methyl-2-pyrrolidinoneReinhard Richter and Henri UlrichCite this: J. Org. Chem. 1973, 38, 15, 2614–2617Publication Date (Print):July 1, 1973Publication History Published online1 May 2002Published inissue 1 July 1973https://pubs.acs.org/do…
The stop-band characteristics of waves in cholesteric-liquid-crystal half-space are investigated using the exact wave solution, the Floquet theorem, and the corresponding Brillouin diagram. The other half-space is filled with a uniform dielectric medium. By appropriate choice of the dielectric constant of the uniform…
Vibrational spectra of a series of halogeno-complex ions of antimony(III) and bismuth(III) are reported. Results of crystal spectra are discussed in terms of the structural environment and a comparative study of Raman solution and solid state spectra is given. Some force constants for hexahalogeno species on a modifie…
Heat capacities of two well characterized polyethylene samples have been measured from 2 to 360 K in a precision vacuum adiabatic calorimeter. The two samples are derived from the same stocks from which NBS standard reference materials (SRM) 1475 and 1476 for linear and branched polyethylene whole polymers, respective…
When describing a crystal structure in terms of the Wyckoff sites occupied, equivalent alternatives often arise because the choice of origin of coordinates is subject to arbitrariness remaining within the standard choice in International Tables for X-ray Crystallography. The problem is explained and simple tables whic…
Vibrational spectra, most of them obtained from Raman scattering, are reported for LiNO3 and NH4NO3 solutions in liquid ammonia, ranging from dilute to the compositions LiNO3/1.6NH3 and NH4NO3/1NH3. All the spectra were obtained from solutions at ambient temperatures. Large changes in the N–H stretching region are cor…