Photoemission for Xe Physisorbed on W(100): Evidence for Surface Crystal-Field Effects

Photoemission spectra at $h\nu =21.2\mathrm{}$ eV reveal two $5p$ levels for xenon physisorbed on a tungsten (100) surface. The spin-orbit splitting of the two levels and their intensity ratio correspond closely to gas-phase measurements, while the $5p_{\frac{3}{2}}$ peak is significantly broadened with respect to the $5p_{\frac{1}{2}}$. We interpret the broadened structure as an unresolved doublet resulting from splitting the Xe $5p_{\frac{3}{2}}$ states in the tungsten-surface crystal field.