Accession Number : AD0267593

Title :   PULSED NUCLEAR MAGNETIC RESONANCE IN ALKTI HALIDES

Corporate Author : CORNELL UNIV ITHACA N Y

Personal Author(s) : CLARK,W.G.

Report Date : JUN 1961

Pagination or Media Count : 1

Abstract : Free induction decay and quadrupolar echo shapes showing the dependence of quadrupolar broadening on the orientation of the crystal relative to the external magnetic field were measured. In all substances studied, quadrupolar broadening disappears at high temperatures. The disappearance is interpreted as arising from the annealing of dislocations, which reappear when the crystal is cooled to room temperature. At temperatures on the order of 600 K diffusion increases the free induction decay lifetimes; at still higher temperatures, free induction decay lifetimes decrease. This decrease is tentatively ascribed to quadrupolar broadening by vacancies. Calculations of the effects of diffusion on the quadrupolar part of free induction decay and echo shapes are presented. These calculations show that diffusion will slow the decay of the quadrupolar part of a free induction decay and attenuate, broaden, and delay the appearance of a quadrupolar echo. A method for the separate measurement transitions in a spin 3/2 system subject to quadrupolar relaxation but not a spin temperature constraint is proposed. The spin echo apparatus used for the experiments is described in detail. (Author)

Descriptors :   *ALKALI METAL COMPOUNDS, *HALIDES, *NUCLEAR MAGNETIC RESONANCE, COMBINATORIAL ANALYSIS, CRYSTAL LATTICES, CRYSTAL STRUCTURE, CRYSTALS, DEFORMATION, DIFFUSION, EXPERIMENTAL DATA, HALF LIFE, INSTRUMENTATION, CARBINOLS, NUCLEAR SPINS, RELAXATION TIME, TEMPERATURE

Distribution Statement : APPROVED FOR PUBLIC RELEASE