title: Ultrafast electron dynamics at water covered alkali adatoms adsorbed on Cu(111).
abstract: Here we report on the ultrafast electron dynamics of the alkalis Na, K, and Cs coadsorbed with D2O on Cu(111) surfaces, which we investigated with femtosecond time-resolved two-photon photoemission. The well known transient electronic binding energy stabilization in bare adsorbed alkalis is enhanced by the presence of water which acts as a solvent and increases the transient energy gain. We observe for all adsorbed alkalis a transient binding energy stabilization of 100-300 meV. The stabilization rates range from 1 to 2 eV ps(-1). Here the heavier alkali exhibits a slower stabilization which we explain by their weaker static alkali-water interaction observed in thermal desorption spectroscopy. The population dynamics at low water coverage is described by a single exponential. With increasing water coverage the behavior becomes non-exponential suggesting an additional excited state due to electron solvation.
authors: Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
authors: Michael
authors: M
authors: Meyer
authors: Ishita
authors: I
authors: Agarwal
authors: Martin
authors: M
authors: Wolf
authors: Uwe
authors: U
authors: Bovensiepen