Dissociative photoionization of H2and D2through the 1sσgionic state

Abstract

The dissociative photoionization of H₂ and D₂ has been investigated experimentally and theoretically from just below threshold to 30.5 eV (405 AA). Experimentally the ratios of the number of dissociated to undissociated photoions H⁺/H₂⁺, D⁺/D₂⁺ have been determined using a mass spectrometric system essentially free from discrimination against ion species. These ratios are found to rise to plateau values of 0.0208+or-0.0017 and 0.0082+or-0.0008 respectively. Over most of the energy range investigated, the photoions are formed solely through the 1s sigma _g ionic state, permitting approximate calculations to be made. A comparison between the calculated and experimental results indicates the need for improved calculations. Significant differences are found on comparing the photoionization data reported with the corresponding values obtained by particle impact.