Dissociative Recombination of H3+ : progress in theory

A. E. Orel, I. F. Schneider, A. Suzor-Weiner
Laboratoire de Photophysique Moleculaire, Université de Paris-Sud, France

1Department of Applied Science, University of California, Livermore, CA 94550, USA
2National Institute for Lasers, Plasma and Radiation Physics, Bucharest-Magurele,Romania
3Laboratoire de Photophysique Moléculaire, Université Paris-Sud and Laboratoire de Chimie Physique, Université Paris 6, Paris, France

Cross section measurements of the dissociative recombination (DR) of ground state H3+ agree on relatively high values. Time-dependent 2D calculations confirm the experimental results at high energy as well as the observed predissociation rates of H3 Rydberg states. However, the value for low-energy DR cross section, deduced from the predissociation rates by an extrapolation procedure, is about 4 orders of magnitude lower than the measured one. A simulation based on multichannel quantum defect theory suggests that an indirect non-adiabatic process may prevail in this case. The model cross section increases by orders of magnitude compared to the extrapolated value when indirect couplings via apparently ineffective channels are properly considered. We are currently performing a new calculation including Rydberg series or "closed channels" in the wave packet propagation. We also explore possible 3D effects (pseudo-rotation) which could enhance the indirect process.