NUCLEAR-QUADRUPOLE INTERACTION OF HIGHLY POLARIZED GAS-PHASE XE-131 WITH A GLASS-SURFACE

We report nuclear magnetic resonance (NMR) experiments on Xe-131 (I=3/ 2) gas-phase atoms which exhibit nuclear quadrupole interaction with t he surface of the sample cell. Nuclear quadrupole coupling constants a nd quadrupole relaxation rates are obtained from the time-domain signa l of the freely precessing nuclear magnetization in weak magnetic fiel ds. The nuclear spin species is polarized by spin-exchange collisions with optically pumped ground-state spins of Rb gas atoms. The Rb atoms also present in the sample are used as a magnetometer to probe the fr ee-induction decay of the nuclear-spin ensemble. The temperature depen dence of both the effective quadrupole splittings and the relaxation r ates are explained by a model for the surface interactions of a Xe ato m adsorbed on the glass surface. The desorption is thermally activated with an activation energy of E(A) =0.12 eV. The surface diffusion of an adsorbed atom is characterized by an activation energy E(D) for the rmally activated hopping between neighboring surface sites. Both energ ies enter the spectral density function governing wall-induced nuclear quadrupole relaxation. Our experimental results lead to the conclusio n that they are on the same order of magnitude.