Knight shift in small platinum particles

We have prepared small platinum particles on Si${\mathrm{O}}_{2}$ by a novel method, and observed the $^{195}\mathrm{Pt}$ nuclear magnetic resonance. The signals are extremely broad, ranging essentially from a field-to-frequency ratio $\frac{{H}_{0}}{{\ensuremath{\nu}}_{0}}=1.14$ G/kHz (as in bulk Pt) to $\frac{{H}_{0}}{{\ensuremath{\nu}}_{0}}=1.10$ G/kHz (which is zero shift by convention). We suggest that the latter value is characteristic for Pt nuclei in a metallic environment at or near a clean surface.