Kiel 2004 – scientific programme

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K: Kurzzeitphysik

K 5: Poster Kurzzeitphysik

K 5.7: Poster

Wednesday, March 10, 2004, 17:45–19:45, Foyer

A model study of molecular isomerization induced by half-cycle and few-cycle infrared pulses — •Christoph Uiberacker and Werner Jakubetz — Institut für theoretische Chemie und Molekulare Strukturbiologie, Universität Wien, Währingerstrasse 17, 1090 Wien, Austria

Using 550 previously calculated vibrational energy levels and dipole moments we performed simulations of the HCN→HNC isomerization dynamics in strong ultrashort laser fields. In the model calculations we used gaussian pulses with 0.5, 1 and 2 optical cycles in the halfwidth. We find that isomerization proceeds via a pump-dump-like mechanism induced by sequential lobes of the pulse, where intermediately many delocalized states are involved. With decreasing number of optical cycles a strong dependence on the carrier envelope phase emerges, while the frequency dependence decreases. For the optimized CEP and pulse length, or frequency, isomerization probabilities of about 45% are obtained using a single few-cycle pulse. In addition by varying system parameters like initial state and number of levels we tried to identify general properties of the dynamics. In this way we were able to build a simple model which describes the successful laser pulse.