Proton kinetic-energy distributions from dissociative photoionization of hydrogen

Measurement of proton kinetic-energy distributions from dissociative photoionization of H₂ is reported, for incident-photon energies up to 41 eV. Data are presented for transitions involving the 1sσg ground state and higher states of H₂⁺. At a photon energy of 41 eV, direct ionization involving the 2pσᵤ state accounts for approximately one-half of the dissociative ionization; other processes, autoionization or direct ionization involving states of higher energy than 2pσᵤ, account for the remainder.