NMR of platinum catalysts. III. Microscopic variation of the Knight shifts

Abstract

The authors report observation of slow beats in the envelope of spin-echo decays in the ${}_{}{}^{195}{}_{}{}^{}\mathrm{Pt}$ NMR of small particles Pt supported on alumina. The beats are shown to arise from the interplay between the Knight-shift inhomogeneity present in the small particles and the pseudoexchange coupling $J$ between neighboring nuclear spins. $\frac{J}{2\pi }$ is found to be 4.2 kHz.