Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 29: Zeitaufgelöste Spektroskopie II
O 29.5: Vortrag
Donnerstag, 27. März 2003, 12:15–12:30, FOE/ORG
Ultrafast Localization Dynamics and Evolution of the Spatial Extent of Solvated Electrons in D2O/Cu(111) — •Martin Wolf, Bovensiepen Uwe, and Gahl Cornelius — Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin
Time- and angle-resolved two-photon photoelectron spectroscopy (2PPE) is used to investigate femtosecond dynamics of electron localization and solvation in ultrathin ice layers adsorbed on Cu(111). Electrons, optically excited in the metal, transfer into the conduction band of the ice layer giving rise to a feature eCB in the angle-resolved 2PPE spectra. Electrons localize within the first 50 fs to form a state eS at 2.9 eV above the Fermi level. The initially positive dispersion of the first moment of eS and eCB shows pronounced changes with time, which indicates a transition from a delocalized to a localized state. After 200 fs an apparent negative dispersion is observed for the localized state, which contains information about the momentum distribution of the localized state with width Δk. Model calculations, which describe the angle-resolved spectra, lead to the conclusion that Δk changes with binding energy during electron solvation and is related to the spatial extent of the solvated electron, as will be discussed in detail.