Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 17: Adsorption II
O 17.2: Vortrag
Dienstag, 28. März 2006, 11:30–11:45, TRE Phys
Correlation of Structure and Femtosecond Electron Dynamics during Crystallization of Amorphous D2O/Cu(111) — •Julia Stähler1, Michael Mehlhorn2, Uwe Bovensiepen1, Karina Morgenstern2, and Martin Wolf1 — 1Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin, Germany — 2Universität Hannover, Institut für Festkörperphysik, Appelstraße 2, 30167 Hannover, Germany
The structure, i.e. molecular arrangement, of an adsorbate layer strongly influences the electron transfer dynamics across the interface since it determines bond strengths and periodicity of the lattice and therefore localized and delocalized states in the adlayer. Using two techniques, low-temperature scanning tunneling microscopy (STM) and time-resolved two-photon photoelectron (2PPE) spectroscopy, we investigate the correlation of the structure and electron dynamics in ultrathin D2O layers on Cu(111). We find that crystallization of initially porous amorphous ice clusters, which are adsorbed at T< 90 K, occurs via three metastable phases. The latter are prepared by annealing to 118 K, 131 K, and 145 K. The stable, crystallized phase is reached by heating to 149 K. These different stages of crystallization are characterized by clear changes in the time-dependent photoelectron spectra. We observe that localization probability and lifetime of the solvated electrons, which are highly sensitive to changes in their local molecular surrounding, strongly depend on the ice structure. Additionally the dependence of image potential states on the ordering in the D2O layer will be discussed.