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Q: Quantenoptik
Q 221: Teilchenoptik
Q 221.1: Talk
Tuesday, March 5, 2002, 16:30–16:45, HS 22/B01
Interference of free electrons by femtosecond laser pulse pair ionization of K atoms — •Matthias Wollenhaupt1, Andreas Assion1, Oksana Bazhan1, Dirk Liese1, Cristian Sarpe-Tudoran1, Marc Winter1, Axel Flettner2, Ullrich Weichmann2, Gustav Gerber2, Sebastian Zamith3, M.A. Bouchene3, Bertrand Girard3, and Thomas Baumert1 — 1Universitaet Kassel, 34132 Kassel — 2Universitaet Wuerzburg — 3Universite Toulouse
The interference of free electrons released from K atoms by a pair of two time delayed 25 fs, 800 nm laser pulses is observed. K atoms in an atomic beam are prepared in an intermediate 5p state via absorption of a 405 nm photon and subsequently ionized from the excited state using two laser pulses with variable delay. Released photoelectrons are detected with temporal resolution in a time-of-flight (TOF) magnetic bottle type spectrometer. At each time delay photoelectron spectra are taken with an energy resolution of 30 meV ranging from threshold electrons at 0.25 eV to the above threshold ionization (ATI) electron energies at 1.8 eV. In order to investigate to which extent the optical coherence is transferred in the electronic continuum and to avoid ambiguities in the interpretation of our results the experiment was carried out with parallel and crossed polarizations of the ionizing radiation. In addition the range of time delays between the two pulses was extended towards values well beyond the temporal overlap of both pulses. In this contribution the oscillations in the photoelectron spectrum at threshold and ATI energies are described and discussed.