The ionization and fragmentation of H2 and CH4 and their deuterated variants by photon impact

The kinetic energy spectra of fragment protons and deuterons produced in the dissociative photoionization of H2, D2, CH4 and CD4 by VUV photons within the energy range 12–50 eV have been measured. Cross sections for negative ion production have also been determined. It is shown that, in addition to direct photoionization, intermediate superexcited states play an important role in these photoionization processes.