ZERO KINETIC-ENERGY PROTON AND DEUTERON PRODUCTION FROM PHOTOIONIZATION OF H-2 AND D-2

A zero ion kinetic energy spectrometer has been developed to study the production of near zero energy protons and deuterons from dissociative photoionization of H-2 and D-2. Both H+ and D+ spectra show four peaks on top of a continuum. The continuum was found to be in excellent agreement with the single center Coulomb calculation for the direct dissociation through the X (2) Sigma(g)(+) state of H-2(+). The observed structures were shown to originate from autoionization of the doubly excited Q(1) (1) Sigma(g)(+)(1), Q(1) (1) Sigma(u)(+)(1), Q(1) (1) Sigma(u)(+)(2), and Q(2) (1) Sigma(u)(+)(1) states, of which the Q(1) (1) Sigma(g)(+)(1) state is dipole forbidden. (C) 1995 American Institute of Physics.