Dissociative ionization of H2 and D2 produced by bombardment with fast He+ ions

Abstract

${\mathrm{H}}^{+}$ and ${\mathrm{D}}^{+}$ energy spectra have been obtained using the time-energy spectroscopy technique. Spectra are presented for ${\mathrm{He}}^{+}$ bombarding energies of 0.5, 1, 2, 3, and 4 MeV. The reflection approximation is used to analyze the spectra and determine the relative contribution to the ${\mathrm{H}}^{+}$ and ${\mathrm{D}}^{+}$ yields of the $1s{\sigma }_g$, $2p{\sigma }_u$, $2p{\pi }_u$, $2s{\sigma }_g$, and double-ionization potential curves of the target molecules. Yield observed in the 2- to 4-eV range suggests that states of ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ which autoionize to the dissociative continuum of the ground $1s{\sigma }_g$ state of ${\mathrm{H}}_2^{+}$ and ${\mathrm{D}}_2^{+}$ contribute to the spectra. The yield is dominated by the excitation of the $2p{\sigma }_u$, $2p{\pi }_u$, and double-ionization potential curves.