A study of the electron–ion dissociative recombination rate constants of the isotopomers of protonated carbon monoxide (HCO+) and formaldehyde (H3CO+)

Abstract

The room temperature electron–ion dissociative recombination (e–IDR) rate constants (αe) for the isotopomers of protonated carbon monoxide (HCO+) and protonated formaldehyde (H3CO+) have been measured using a flowing afterglow equipped with an electrostatic Langmuir probe. The isotopomers included in this study and their corresponding e–IDR rate constants are H312CO+, 7.4×10−7cm3s−1; H313CO+, 6.8×10−7cm3s−1; H12CO+, 2.0×10−7cm3s−1; H13CO+, 1.8×10−7cm3s−1; D12CO+, 1.6×10−7cm3s−1; and D13CO+, 1.4×10−7cm3s−1. The recombination rate constants for the measured isotopomers exhibit a decrease in the rate constant with the addition of a heavy isotope. This effect is greater with a hydrogen/deuterium substitution than with a 12C/13C substitution. The comparison of the current data with previously published data is discussed.