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Title: Deuterium and selenium-77 NMR study of the condensed phases of hydrogen selenide

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 5.7more » 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.« less
Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
5818414
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Phys. Chem.; (United States); Journal Volume: 90:10
Research Org:
Dalhousie Univ., Halifax, Nova Scotia
Country of Publication:
United States
Language:
English
Subject:
37 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 400201* -- Chemical & Physicochemical Properties