ABSOLUTE CROSS-SECTIONS FOR DISSOCIATIVE RECOMBINATION OF HD- COMPARISON OF EXPERIMENT AND THEORY( )

Absolute cross sections for dissociative recombination of HD+ were mea sured in the ion storage CRYRING for incident electron energies in the range 0.01-20 eV. The ions were stored for about 25 s before data tak ing, which is several orders of magnitude longer than their vibrationa l lifetimes towards spontaneous emission of infrared radiation. A broa d resonance in the cross section at 5-12 eV is due to recombination in to a manifold of doubly excited states. Multichannel quantum-defect th eory was used to calculate the absolute cross section of this resonanc e. The calculations required inclusion of different mechanisms, such a s dissociative autoionization, and many molecular states in order to r eproduce the resonance region. Very good agreement of experiment and t heory is found, and the results strongly reinforce that vibrationally cold ions were used in the experiment.