Ultrafast electron dynamics at water covered alkali adatoms adsorbed on Cu(111)

作者：Meyer Michael; Agarwal Ishita; Wolf Martin; Bovensiepen Uwe^*

来源：Physical Chemistry Chemical Physics, 2015, 17(13): 8441-8448.

DOI：10.1039/c4cp05356g

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.

• 出版日期2015