Dissociative charge transfer of He+ ions with H2 and D2 molecules from 78 to 330 K

Abstract

The dissociative charge transfer of He⁺ ions with H₂ and D₂ molecules has been studied using a temperature‐variable drift‐tube mass‐spectrometer apparatus over the temperature range 78 to 330 K. The binary rate coefficients are small at 300 K, ∼10⁻¹³–10⁻¹⁴ cm³/sec, and only slightly larger at 78 K. Termolecular contributions to the binary rate coefficients are found to be small at 330 K but increase substantially with decreasing temperature. Two‐body charge transfer with D₂ is found to be slower than with H₂ by a factor of 10, in good agreement with recent theoretical predictions, although the measured values of the rate coefficients are larger by a factor of ∼4 than the predicted values.