Femtosecond dynamics of the laser-excited Cs/Cu(111) system: Interplay of the electronic and nuclear evolutions

The Cs/Cu(111) system presents a very long-lived excited electronic state, the excitation of which induces the Cs adsorbate desorption. The effect of the Cs motion on the electronic state dynamics is studied within a wave-packet propagation approach. The computed excited state time evolution exhibits features that are very close to those observed in time-resolved-2-photon-photo-emission (TR-2PPE) experiments, stressing the strong influence of the Cs motion on the electron dynamics. In addition, it is shown that taking into account the effect of the Cs motion can qualitatively change the interpretation of some physical observables.