Nuclear spin-lattice relaxation in solid cuprous halides

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Abstract
Measurements have been made by pulsed NMR of the spin-lattice relaxation times T1 of 63Cu, 65Cu and 81Br nuclei in three polycrystalline cuprous halides of zinc blende structure from 78 to 300 K. The temperature dependence of T1 is well described by Van Kranendonk's temperature function and testifies to a two-phonon quadrupolar relaxation mechanism. The ratio of values of T1 for 63Cu and 65Cu is in all cases in good agreement with the inverse square of their quadrupole moments. The fivefold increase in T1 for copper nuclei on proceeding from CuCl through CuBr to CuI is attributed predominantly to its dependence on the thirteenth power of the lattice parameter. Values of gamma , the parameter characterizing antishielding and other effects, of order 103 are required to account for absolute values of T1.