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 5.7 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.
- Research Organization:
- Dalhousie Univ., Halifax, Nova Scotia
- OSTI ID:
- 5818414
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 90:10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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