			15min:

STUDIES OF THE TEMPERATURE DEPENDENCE AND EXCITATION OF THE PRODUCTS OF DISSOCIATIVE ELECTRON RECOMBINATION OF N₂H⁺ AND HCO⁺ IONS.

V. POTERYA, J. L. MCLAIN, L. M. BABCOCK AND N. G. ADAMS, Department of Chemistry, University of Georgia, Athens, GA 30602, USA.

The dissociative recombination (DR) rate constants of N₂H⁺/N₂D⁺ and HCO⁺ ions with electrons have been measured as a function of temperature (100 - 500 K) using the Flowing Afterglow Langmuir Probe (FALP) technique. N₂H⁺ and HCO⁺ ions are two of the most abundant ions detected in the interstellar medium. The results cannot be expressed either by the power law T^-0.5 of the direct DR mechanism or the power law T^-1.5 of the indirect DR mechanism. In order to further understanding of the results, a study of the vibrational state distributions of the N₂(B³ _g) electronically excited products for the N₂H⁺ and N₂D⁺ recombinations at 100 K has been carried out using an atmospheric pressure monochromator. Comparison has been made with previous results obtained at 300 K . The substantial enhancement of the vibrational level ( ' = 6) detected from the N₂ B state for N₂H⁺ recombination over N₂D⁺ recombination is consistent with previous results and can be explained by the influence of a tunneling mechanism of DR. Funding from NASA Grant No. NAG5-8951 is gratefully acknowledged.