LASER STUDIES OF AUTOIONIZATION PROCESSES IN MOLECULAR $HYDROGEN^{1}$
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Date
1989
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Recent results of optical-optical double resonance studies of rotational and vibrational autoionization in molecular hydrogen will be reported. In the experiments on rotational autoionization, one laster was used to excite a two-photon transition to the $E, F, ^{I}\Sigma^{+}_{g} v'=EO, J'=O-4$ levels, and a second laser was used to probe single photon transitions to the rotationally autoionized np Rydberg series converging to the $X ^{2}\Sigma^{+}_{g}, v^{+}=0, N^{+}=1-6$ rotational levels of the $ion.^{2}$ Of the five dipole allowed Rydberg series converging to $v^{+}=D$ excited from each intermediate J' level $(J'>2)$, two are allowed to rotationally autoionize in a coupling scheme that assumes ejection of pure p-waves in the ionization process and singlet coupling of the spins of the ion core and the outgoing electron. As expected, members of these Rydberg series have large half-widths. Ionization is also observed for the series that are forbidden to rotationally autoionize according to this simple coupling scheme, and the possible decay mechanisms will be discussed. In experiments on vibrational autoionization, rotationally resolved photoelectron spectra were recorded for members of the np Rydberg series converging to the $x ^{2}\Sigma^{+}_{g}, v^{+}=1, \bar{N}^{+}=1$ and $\bar{N}^{+}=3$ levels of the ion. The results will be compared with a simple model and the significant deviations from this model will be discussed.
Description
$^{1}$ Work supported by the U.S. Department of Energy, Office of Health and Environmental Research, under Contract W-31-109-Eng-38. $^{2}$ M. A. O'Halloran, P. M. Dehmer, S. T. Pratt, J. L. Dehmer, and F. S. Tomkins, J. Chem. Phys. 90, 930 (1989).
Author Institution: Argonne National Laboratory; Department of Physics and Astronomy, University of Oklahoma
Author Institution: Argonne National Laboratory; Department of Physics and Astronomy, University of Oklahoma