Regensburg 2004 – scientific programme

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O: Oberflächenphysik

O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)

O 14.7: Poster

Monday, March 8, 2004, 18:00–21:00, Bereich C

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

In the last years, coherent control of chemical reactions 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 application of the pulse shaping technique to the optimization / manipulation of ultrafast surface processes, such as surface chemical reactions.

The apparatus used to shape 20 fs pulses consists of an all-reflective zero-dispersion compressor in combination with a programmable 640-stripe liquid crystal spatial light modulator (SLM). A closed loop setup, controlled by an evolutionary algorithm [3], iteratively achieves optimization of an experimental signal which is used as feedback. We find that the Two-Photon-Photoemission Yield, e.g. measured from an adsorbate resonance on the system Cs/Cu(111), is a possible detection scheme that enables us to control specific surface-related properties. The experimental setup, preliminary results and future prospects will be discussed.

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

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

[3] D. Zeidler et al.: Phys. Rev. A 64, 023420 (2001)