J. St�hlera, J.-C. Deinerta, D. Wegkampa, Uwe Bovensiepenb and M. Wolf*aa Fritz-Haber-Institut of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germanyb University of Dusiburg-Essen, Dept. of Physics, Lotharstr. 1, 47048 Duisburg , Germany*presenting author, email: wolf@fhi-berlin.mpg.deElectron transfer across interfaces is of vital importance in various areas of physics, chemistry and biology. In these processes often an excess charge is transferred across an interface between different materials and is subsequently screened by the reorientation of a surrounding molecular environment. We use surface science techniques combined with time-resolved two-photon-photoemission (2PPE) spectroscopy to study the ultrafast dynamics of interfacial electron transfer at several hybrid interfaces: (1) Amorphous D2O ice layers on a Cu(111) surface serve as a model system to study ultrafast dynamics of electron injection, localization and solvation in the polar adlayer as well as charge transfer back to the metal substrate. (2) Furthermore, we employ 2PPE spectroscopy to investigate the occupied and unoccupied electronic structure and the electron dynamics at the pyridine/ZnO(10-10) interface as an example for a hybrid system of inorganic and organic semiconductors. Characterization of the pristine ZnO(10-10) surface yields the position of the valence and conduction band (CB) edge energies and surface charge accumulation upon hydrogen termination leading to a metallic surface. Adsorption of pyridine leads to a substantial work function reduction up -2.7 eV which strongly affects the energy level alignment at the inorganic/organic interface. Finally we directly monitor hot electron relaxation and exciton formation at the ZnO surface on fs- to ps timescales.

Ultrafast dynamics of interfacial electron transfer

246th National Meeting (2013)

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