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Author Facey, G. ♦ Wasylishen, R. E. ♦ Collins, M. J. ♦ Ratcliffe, C. I. ♦ Ripmeester, J. A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ DEUTERIUM ♦ NUCLEAR MAGNETIC RESONANCE ♦ SELENIDES ♦ KINETICS ♦ SELENIUM 77 ♦ EXPERIMENTAL DATA ♦ ISOTOPE EFFECTS ♦ LATTICE VIBRATIONS ♦ LOW TEMPERATURE ♦ MEDIUM TEMPERATURE ♦ SOLIDS ♦ SPECTRAL SHIFT ♦ VERY LOW TEMPERATURE ♦ CHALCOGENIDES ♦ DATA ♦ EVEN-ODD NUCLEI ♦ HYDROGEN ISOTOPES ♦ INFORMATION ♦ INTERMEDIATE MASS NUCLEI ♦ ISOMERIC TRANSITION ISOTOPES ♦ ISOTOPES ♦ LIGHT NUCLEI ♦ MAGNETIC RESONANCE ♦ NUCLEI ♦ NUMERICAL DATA ♦ ODD-ODD NUCLEI ♦ RADIOISOTOPES ♦ RESONANCE ♦ SECONDS LIVING RADIOISOTOPES ♦ SELENIUM COMPOUNDS ♦ SELENIUM ISOTOPES ♦ STABLE ISOTOPES ♦ Chemical & Physicochemical Properties
Abstract Hydrogen selenide has been studied by /sup 2/H and /sup 77/Se NMR between 57 and 273 K, in order to characterize the molecular motions. In solid III the molecules are essentially rigid at approx. 77 K, but there is evidence for the onset of a slow motion just before the transition to phase II. The III equivalent to II phase transition shows hysteresis. At 77 K the /sup 77/Se rigid lattice shielding tensor components were found to be sigma/sub xx/ = - 240.7, sigma/sub yy/ = -9.5, and sigma/sub zz/ = 250.2 ppm relative to sigma/sub isotropic/. The /sup 2/H line shape at 77 K indicated a quadrupole coupling constant (e/sup 2/qQ/h) = 102.6 kHz and asymmetry parameter eta = 0.113, whereas in phase II at 120 K(e/sup 2/qQ/h) = 56.9 kHz, eta = 0 and in supercooled phase II at 85 K eta = 0.059. In the plastic crystalline phase I both /sup 2/H and /sup 77/Se line shapes are completely averaged by rapid overall rotations. Apparent activation energies of 3.5 kJ mol/sup -1/ (solid I) and 3.4 kJ mol/sup -1/ (liquid) were obtained from /sup 2/H T/sub 1/ measurements, and 4.3 kJ mol/sup -1/ (solid I) and 5.7 kJ mol/sup -1/ (liquid) were obtained from /sup 77/Se T/sub 1/ measurements. The /sup 77/Se spectra show a large deuterium isotope shift of 7 ppm per deuterium, and the chemical shift also shows large discontinuities at the gas-liquid-solid I phase transitions. 45 references, 6 figures, 4 tables.
Educational Use Research
Learning Resource Type Article
Publisher Date 1986-05-08
Publisher Department Dalhousie Univ., Halifax, Nova Scotia
Publisher Place United States
Journal J. Phys. Chem.
Volume Number 90
Issue Number 10
Organization Dalhousie Univ., Halifax, Nova Scotia


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