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 15.75: Poster

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

Limitations in the use of a 2D hemispherical energy analyser for PES in combination with a low-repetitive ultrashort photon source — •S. Mathias¹, O. Heinz², S. Passlack¹, D. Mittnacht¹, V. Temnov², M. Bauer¹, D. von der Linde², and M. Aeschlimann¹ — ¹FB Physik, TU Kaiserslautern, 67663 Kaiserslautern — ²Institut für experimentelle Physik, Uni Duisburg Essen, 45117 Essen

One of the main advantages of hemispherical electron analysers equipped with a 2D detector is their high efficiency due to the parallel detection scheme with respect to energy and momentum. It makes these systems highly preferable for specific applications e.g. for the use with low-repetitive photon sources such as laser-based femtosecond UV-sources. In this study a 2D analyser has been used for 2 Photon Photoemission spectroscopy from an occupied surface state of Cu(111) using a 1 kHz laser amplifier system. For comparison, corresponding data have also been recorded using a ToF electron analyzer and a high repetitive (80 MHz) Ti:Sapphire laser. Particular focus has been set on the spectral broadening due to space charge effects which become apparent at sufficient high pulse intensities from the 1 kHz amplifier. The experimental data are compared with numerical simulations which support the relevance of space charge effects. Our results show that the 2D analyzer scheme is suitable for high-resolution angular-resolved electron spectroscopy in combination with low repetitive laser sources and may in the future be used complementary to conventional ToF-detectors.