Table of Contents
Journal of Atomic, Molecular, and Optical Physics
Volume 2011, Article ID 410108, 9 pages
Review Article

Multiphoton Ionization and Fragmentation of Hydrogen Chloride: A Diatomic Still Good for a Surprise

1Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
2Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia

Received 1 October 2010; Revised 14 February 2011; Accepted 3 March 2011

Academic Editor: B. A. Malomed

Copyright © 2011 Christof Maul et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The competition between multiphoton ionization and fragmentation in the diatomic molecule hydrogen chloride is reviewed. Emphasis is laid on recent experimental results employing chemical imaging methods in order to obtain kinetic energy distributions and angular distributions of photoproducts. The energy range considered is 15 to 20 eV, equivalent to the absorption of three or four photons in the ultraviolet wavelength range. The role of Rydberg states as resonantly excited intermediate states in the ionization/fragmentation processes is assessed. Mixing among states gives rise to peculiarly shaped double minimum potential energy curves which allow for the production of hydrogen and chlorine atomic and ionic fragments via several competing pathways, in addition to the production of molecular HCl+ ions. States with different electronic properties show a qualitatively different behaviour from states. Accidental resonances between states of differing orbital angular momentum or multiplicity serve to override these differences and cause subtle as well as significant deviations from the unperturbed behaviour.