Evidence of H2+ dynamical alignment in short laser pulses

Fatima Anis, B.D. Esry
James R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS, USA

We will present theoretical results for H2+ dissociation in 10-135 fs laser pulses from calculations including nuclear vibration, rotation, and electronic excitation. Nuclear rotation has commonly been neglected for dissociation in short pulses with the nuclei usually considered to be fixed along laser polarization. We will show that the comparison of the total dissociation probability between calculations with nuclear rotation and without it proves to be a good way to quantify dynamical alignment. For example, we find a large difference in the total dissociation probabilities from the two calculations, indicating that there is significant dynamical alignment of H2+ for 135 fs pulses and even for 45 fs pulses. For 10 fs pulses, though, the difference is small, hence there is little dynamical alignment. Our results indicate, however, that the angular distribution of the dissociating fragments can not be obtained correctly --- even for very short pulses like 10 fs --- when nuclear rotation is neglected. It is therefore important to include nuclear in calculations to obtain results directly comparable with the experiments.

This work was supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, and by the National Science Foundation.

Presented at DAMOP, May 2008, in State College, PA.


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