The role of Rydberg states in H+2dissociative recombination with slow electrons

The cross section for H + 2 dissociative recombination with slow electrons is calculated using the multichannel quantum defect theory, with the set of molecular data used for the recent study of H+H* associative ionization by Urbain et al. Excited vibrational levels of s sigma g and d sigma g Rydberg states show up as broad resonances, mostly dips, in satisfying agreement with the vibrationally selected measurements of Mitchell et al. The authors analyse the mechanisms for resonance formation and discuss the adequacy of the theoretical treatment.