Hamburg 2009 – scientific programme

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A: Fachverband Atomphysik

A 34: Poster II

A 34.36: Poster

Thursday, March 5, 2009, 16:30–19:00, VMP 9 Poster

Selective excitation of multiple states in atomic sodium by a single chirped femtosecond laser pulse — Marc Krug¹, Svetoslav Ivanov², Matthias Wollenhaupt¹, Tim Bayer¹, •Christian Lux¹, Nikolay V. Vitanov², and Thomas Baumert¹ — ¹Universität Kassel, Institut für Physik und Center for Interdisciplinary Nanostructure Science and Technology (CINSaT), Heinrich-Plett-Str. 40, D-34132 Kassel, Germany — ²Theoretical Physics Division - Department of Physics, Sofia University - James Bourchier 5 blvd, 1164 Sofia, Bulgaria

Chirped femtosecond laser pulses generated by spectral phase modulation are used for strong-field Resonance Enhanced Multi-Photon Ionization (REMPI) of atomic sodium. Photoelectron Angular Distributions (PADs) are measured employing a photoelectron imaging spectrometer. Pronounced differences in the PADs with respect to the sign of the chirp (up-chirp/down-chirp) are observed experimentally. We identify three contributing ionization processes, i.e. a (2+1+1) REMPI, a (3+1) REMPI and ionization via the off-resonant 3p-state. The experimental data is supported by full quantum mechanical simulations of the excitation/ionization process. An analytical model to describe the (2+1+1) excitation channel and the selective excitation of multiple states is presented in addition.