Dissociative photoionization of H2 at 26.9 and 30.5 eV

Abstract

A quantal resonance formalism is applied to the calculation of the cross sections for the absorption of photons of energies 26.9 and 30.5 eV into a ¹Σ⁺_u resonance Rydberg state of H₂. The ¹Σ⁺_u state undergoes autoionization into the vibrational continuum of the ²Σ⁺_g state of H⁺₂, producing energetic H⁺ ions. The calculations reproduce state of H⁺₂, producing energetic H⁺ ions. The calculations reproduce the maxima in the measured cross sections at H⁺ energies near 3.2 eV for overestimate the cross sections below 2.5 eV. An arbitrary reduction in the autoionizing widths by a factor of 2 restores agreement over the measured energy range, though more elaborate calculations of the widths suggest that values should be increased.