Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 15: Postersitzung (Adsorption an Oberfl
ächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Rastersondentechniken, Zeitaufgelöste Spektroskopie, Methoden)

O 15.74: Poster

Freitag, 4. März 2005, 17:00–20:00, Poster TU D

Manipulation of ultrafast surface processes using fs-pulse shaping — •Felix Steeb, Marlies Wessendorf, Jörg Lange, Alexander Mönnich, Stefan Mathias, Martin Aeschlimann, and Michael Bauer — FB Physik, TU Kaiserslautern, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern

In recent years, coherent control of ultrafast processes in the gas phase [1] or in the liquid phase [2] by means of adaptive femtosecond pulse shaping has been demonstrated.

In this paper, we present first attempts to employ the pulse shaping technique to the manipulation of ultrafast surface processes, such as surface chemical reactions.

For the Two-Photon-Photoemission (2PPE) yield from the occupied shockley surface state of a Cu(111) surface, we find a complex dependence on the spectral phase of the exciting pulse, modulated by a programmable 640-stripe liquid crystal spatial light modulator incorporated into a conventional 4f-setup. Resonance enhanced excitation induced by an unoccupied adsorbate state, e.g. Cs/Cu(111), modifies this dependence. Model calculations within the framework of the Liouville-von-Neumann equitations can qualitatively reproduce the experimental data. Future prospects, e.g. possible schemes to control a surface chemical reaction using pulse-shaping techniques and other potential applications are discussed.

[1] - A. Assion et al.: Science 282, 919 (1998)

[2] - T. Brixner et al: Nature 414, 57 (2001)