Dissociation and ionization of HD$^{+}$ in intense few-cycle laser pulses
P. Q. Wang,
A. M. Sayler,
V. Roudnev,
B. Gaire,
Nora G. Johnson,
M. Leonard,
E. Parke,
K.D. Carnes,
B. D. Esry,
I. Ben-Itzhak
( J. R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan KS 66506)
All the dissociation and ionization channels of an HD$^{+}$ molecular ion
beam exposed to intense laser fields, namely H$^{+}$+D, D$^{+}$+H and
H$^{+}$+D$^{+}$, have been studied simultaneously using a 3D coincidence
momentum imaging method. These breakup channels are experimentally separated
from each other. The laser pulse durations are from about 8 fs up to those
comparable to the dissociation time scale of the molecule, with a wavelength
of 790 nm and an intensity range of 10$^{13}$-10$^{15}$ W/cm$^{2}$. The
focus of this study is on the phenomena in few-cycle laser pulses. The 3D
momentum of each fragment is retrieved from its position and time signals,
which provides angular and kinetic energy release spectra for each breakup
channel. The dissociation of HD$^{+}$ is found to be governed by
bond-softening and above threshold dissociation, depending on the laser
intensity. The ionization of HD$^{+}$ is strongly aligned along the laser
polarization and has a broad kinetic energy distribution which shifts to
higher values at higher intensity.
This work was supported by the Chemical Sciences, Geosciences and Biosciences Division,
Submitted to DAMOP, May 2006 in Knoxville, TN.
Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, and by
the National Science Foundation.
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