Photoassociation of metastable heliumA. S. Dickinson1, F. X. Gadéa2 and T. Leininger3
1 School of Natural Sciences (Physics), University of Newcastle - Newcastle, NE1 7RU UK
2 The Nano Science Group, CEMES, CNRS UPR 8011 29 rue J. Marvig, BP 4347, F-31055 Toulouse, France
3 Laboratoire de Physique Quantique, UMR 5626 du CNRS, Université Paul Sabatier 118 Route de Narbonne, F-31062 Toulouse Cedex 04, France
received 16 December 2004; accepted in final form 10 March 2005
published online 25 March 2005
A theoretical study is performed for the photoassociation of metastable helium. Combining short-range, high-level, ab initio calculations for and symmetries and long-range behaviour, better described in Hund's case (c), potential-energy curves for attractive, and , as well as repulsive, and , states of quintet metastable helium molecules dissociating to are obtained. Taking into account the atomic spin-orbit couplings, vibrational levels are derived for near-dissociation levels at the 3P2 asymptote. Comparison with results from three recent photoassociation experiments obtained under different conditions (K temperatures with spin alignment and mK temperatures without) allowed for an assignation of about three quarters of the observed levels. The robustness of the vibrational numbering is confirmed by testing a modification of the short-range potentials.
31.50.Df - Potential energy surfaces for excited electronic states.
32.80.Pj - Optical cooling of atoms; trapping.
33.20.Kf - Visible spectra.
© EDP Sciences 2005