Observation of Conduction-Electron Density Oscillations at the Surface of Platinum Particles

Abstract

Anomalously large $^{195}\mathrm{Pt}$ NMR linewidths have been observed in platinum particles with diameters ranging from 33 \AA{} to 200 \AA{}. Spin-echo measurements revealed the presence of nuclear spin-exchange diffusion in large magnetic field gradients attributable to the large indirect exchange interaction in platinum. These data indicate that there are electron spin-density oscillations near the platinum surface consistent with a simple model ascribing free-electron behavior to the $s$-like conduction electrons.