Dissociation dynamics of hydrogen molecular ions in ultrafast intense laser fields

Pengqian Wang, Jiangfan Xia, Kevin D. Carnes, A. Max Sayler, Mark A. Smith, Itzik Ben-Itzhak
(Kansas State University)

We have experimentally explored laser-induced dissociation of H_2^+ using coincidence 3D momentum imaging. The vibrationally excited molecular ion beam (4-5 keV) is crossed by an ultrafast intense laser beam (45-135 fs, 10^13-10^14 W/cm^2). The resulting fragments are recorded in coincidence by a position-sensitive detector. Complete angular distribution and kinetic energy release maps are reconstructed from the measured dissociation-momentum vectors. Various effects due to the laser-induced potential, such as bond-softening, trapping, and level shifting have been observed in the vibrationally resolved kinetic energy distribution. The dissociation of these vibrational states exhibits threshold behavior as well as stronger alignment of the lower states, suggesting a time order in their dissociation caused by the increasing laser intensity.

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.

Submitted to DAMOP, May 2004 in Tucson, AZ.

 

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