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91.
92.
C. Stassis D. Arch J. Zarestky O.D. McMasters B.N. Harmon 《Solid State Communications》1980,35(3):259-261
We measured the phonon dispersion curves of hcp Hf at 295, 800, and 1300 K. We find that (unlike the other modes) the zone center [001]LO mode softens appreciably as the temperature decreases and at room temperature this branch exhibits a dip at the zone center. This anomalous behavior is similar to that observed in hcp Zr, Ti, and Tc and seems to be characteristic of the hcp superconducting elements. 相似文献
93.
C.G. Olson J.H. Sexton D.W. Lynch A.J. Bevolo H.R. Shanks B.N. Harmon W.Y. Ching D.M. Wieliczka 《Solid State Communications》1985,56(1):35-37
The valence bands of epitaxial layers of A1N were studied by ultraviolet photoelectron spectroscopy and electron energy loss spectroscopy. A self-consistent band structure was calculated and the resultant density of states compared with the UPS spectra. Qualitative agreement was good, with discrepancies arising primarily from the neglect of dipole matrix elements. 相似文献
94.
In metallic form Eu and Gd both have seven unpaired 4f electrons in an 8S state; surprisingly, however, Eu impurities are only half as effective as Gd in lowering the superconducting transition temperature of dhcp La. This implies a much smaller 4f conduction electron coupling for Eu — a result which we show is in quantitative agreement with Dirac-Fock calculations. 相似文献
95.
Several exact results are presented for a one-dimensional tight-binding model of layered binary metallic structures for the cases of arbitrary, random, incommensurate, and commensurate layer sequences. 相似文献
96.
Kenneth M. Harmon Susan L. Madeira Marshan J. Jacks Günsel F. Avci Anne C. Thiel 《Journal of Molecular Structure》1985,128(4):305-314
The infrared spectrum of the OHF hydrogen bond in choline fluoride is completely different from the spectra of the electrostatic O—H?X hydrogen bonds in the other choline halides; however, this spectrum cannot be accounted for in terms of a “very strong” covalent OHF bond such as those found in carboxylic acid—fluoride ion complexes or postulated for betaine hydrofluoride. The spectrum of choline fluoride is interpreted best in terms of an intermediate type of unsymmetrical hydrogen bond (r° O?F = ~ 256 pm) which shows strong intensity enhancement for the first overtone of the OHF bending vibration. 相似文献
97.
98.
Thermal desorption of coal fly ash in a flowing stream of helium liberates volatile compounds which are collected on Tenax resin. A chemical “fingerprint” of these components collected from the fly ash is obtained by using thermal desorption of the material collected on the Tenax resin and capillary-column gas chromatography. Compounds ranging in volatility from that of benzene (b.p. 80°C) through C1-phenanthrene (b.p. ca. 360°C) are detected, but recoveries of components only through naphthalene (b.p. 218°C) are suitable for quantitative work. The method provides chemical information on volatile organic compounds complementary to that achieved by procedures based on solvent extraction. 相似文献
99.
The observation of a rotating frame Larmor frequency dependence in the proton spin relaxation of glycerol lends support to a recent study of proton spin relaxation in this substance. Comparison of the data to recent theories describing spin relaxation by translational diffusion strongly suggest that this is the dominant relaxation process in glycerol near room temperature. In addition, the measurement of the self-diffusion coefficient of glycerol, at a temperature lower than has been previously reported, indicates that this rotating frame technique may be useful in the study of diffusion in viscous media. 相似文献
100.