Electronic Resonances in Rare-Gas Adsorbates Observed by Spin-Resolved Electron Spectroscopy

Recent experimental results of spin-polarized electron emission following photoexcitation of the valence orbitals of adsorbed rare-gas atoms are presented. As light source we employed the circularly polarized synchrotron radiation from the storage ring BESSY (Berlin). As detection technique served angle- and spin-resolved electron spectroscopy. The resolution of the experimental method is demonstrated by the example of photoemission from Ar on Pt(111), where a doublet feature with a splitting of only 90 meV could be resolved, which is hardly discernible in intensity spectroscopy. Below the threshold for direct photoemission narrow electronic resonances have been observed, resulting from discrete np → n's excitations in the adsorbate. For the system Xe on Ir(111) the dependence of the resonance features on the coverage from the sub-monolayer regime up to the 3D-crystal is discussed.