Düsseldorf 2007 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 23: Poster II - Interaction with strong or short laser pulses

A 23.3: Poster

Donnerstag, 22. März 2007, 16:30–18:30, Poster B

Asymmetry in the photoelectron angular distribution by two-photon chirped excitation of sodium atoms — •Marc Krug, Matthias Wollenhaupt, and Thomas Baumert — Experimentalphysik III, CINSaT, Fachbereich Physik, Universität Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel

Chirped femtosecond laserpulses generated by spectral phase modulation are used for strong field two-photon excitation and ionization of atomic sodium. Angular resolved photoelectron spectra are measured using a photoelectron imaging spectrometer. Pronounced asymmetries in the photoelectron angular distribution with respect to the sign of the chirp (upchirp/downchirp) are observed experimentally. We present an analysis of the effect based on chirped excitation of a three-level system. Fine details of the excitation/ionization process in sodium are analyzed in terms of numerical calculations on a multi-level system.