OH PRODUCTION IN THE DISSOCIATIVE RECOMBINATION OF H3O+, HCO2+, AND N2OH+ - COMPARISON WITH THEORY AND INTERSTELLAR IMPLICATIONS

The percentages of OH radicals produced in the dissociative recombination reactions of H3O+, HCO2+, and N2OH+ with electrons at 300 K have been determined to be (65 ± 15)%, (34 ± 8)%, and (31 ± 8)%, respectively. The experiments were conducted using a flowing afterglow/Langmuir probe (FALP) apparatus modified to include spectroscopic diagnostics. In the case of H3O+, the amount of OH produced is intermediate between the theoretical predictions of Bates and of Herbst. The importance of this finding in determining the dominant oxygen containing species in dense interstellar clouds is discussed in relation to recent chemical models of these clouds. In the case of HCO2+, it is concluded that recombination will be a significant overall loss process for HCO2+, and thus CO2, in dense interstellar clouds for fractional electron abundances greater than ̃10-8.