Darmstadt 2008 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 18: Femtosekundenspektroskopie

MO 18.7: Poster

Dienstag, 11. März 2008, 14:00–19:00, Poster C1

High Harmonic Generation on Molecular Excited Electronic States — •Markus Gühr, Brian K. McFarland, Joe P. Farrell, and Philip H. Bucksbaum — Stanford PULSE Center, Stanford University and SLAC, California, USA

We discuss schemes for the generation of high harmonics on excited electronic states of molecules. The high harmonic generating pulse is used to probe the dynamics initiated with a first pump pulse. This opens the chance to observe dynamics on those states without involving other electronic states in a probe process.

The main difficulty arising is the low ionization potential and thus the inherent high ionization rate for molecules in the excited state. We present a method to overcome this problem using the symmetry of the molecular wave function.

A further complication is given by the fact that a small harmonic signal from the excited state is sitting on a big background from molecules in their electronic ground state. Four-wave-mixing techniques can be applied to generate a background-free signal. We present prototypical four-wave-mixing measurements, using the third harmonic generated in air.