Photostimulated desorption of Xe from Au(001) surfaces via transient Xe⁻ formation

Photostimulated desorption (PSD) of Xe atoms from the Au(001) surface in thermal and nonthermal regimes was investigated by the time-of-flight measurement at photon energies of 6.4 and 2.3 eV. Xe was desorbed in a thermal way at high laser fluence, which was in good agreement with theoretical simulations. At a low laser fluence, on the other hand, desorption was induced only at a photon energy of 6.4 eV by a nonthermal one-photon process. We argue that the nonthermal PSD occurs via transient formation of Xe⁻ on Au(001). The lifetime of Xe⁻ is estimated to be ∼15 fs with a classical model calculation. Whereas the electron affinity of Xe is negative in the isolated state, it is stabilized by the metal proximity effect.