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O: Oberflächenphysik

O 35: Hauptvortrag Bauer

O 35.1: Hauptvortrag

Donnerstag, 11. März 2004, 14:00–14:45, H36

Femtosecond ultraviolet photoelectron spectroscopy for the study of ultrafast surface processes — •Michael Bauer — Fachbereich Physik, TU Kaiserslautern, 67663 Kaiserslautern, Deutschland

The technique of ultraviolet photoelectron spectroscopy allows detailed insights into static properties of molecular adsorption such as bond character, adsorption geometry or intermolecular interaction.

In combination with an optical pump-probe scheme this technique can in principle also be used to monitor changes in the adsorbate state on a femtosecond time-scale and, in consequence, the evolution of the chemical surface state during the course of a chemical reaction. This has become possible by the development of laser-driven short-pulse EUV sources delivering sub-10 fs pulses at photon energies of up to 500 eV.

Recent experimental results will be presented that show the potential of time-resolved UPS for such studies. In particular it is possible to identify and follow different steps within a surface chemical reaction at a time-resolution < 50 fs. This includes the electronic excitation of the system under investigation, the consequent change in the chemical state of an adsorbed molecule and the real-time observation of a vibrational excitation of the adsorbate.