Molecular frame photoelectron angular distributions in dissociative photoionization of H2 in the region of the Q1 and Q2 doubly excited states

Dissociative photoionization of H-2 induced by VUV linearly polarized synchrotron radiation P has been studied using the (VH+ V-e, P) vector correlation method. The ion-electron kinetic energy correlation diagrams obtained for the three photon excitation energies hv = 20, 28.5 and 32.5 eV enable us to identify and select the dominant dissociative photoionization processes. The Ichi(theta(e), phi(e)) molecular frame photoelectron angular distributions for any orientation chi of the molecular axis with respect to the polarization are reported for direct photoionization of H-2 into the H-2(+) ((2)Sigma(g)(+)) ionic ground state at hv = 20 eV and for the dominant DPI processes involving autoionization of the H-2(Q(1) 1Sigma(u)(+)(1)) and H-2(Q(2) 1Pi(u)(1)) doubly excited states into the H-2(+)((2)Sigma(g)(+)) and H-2(+)((2)Sigma(u)(+)) continua at hv = 28.5 and 32.5 eV They show the dominant excitation of a psigma(u) partial wave in autoionization of the Q(1)((1)Sigma(u)(+)(1)) state into the H-2(+)(1ssigma(g)) ionic state and that of a dpi(g) partial wave in autoionization of the Q(2)((1)Pi(u)(1)) state into the H-2(+)(2psigma(u)) continuum. A molecular frame forward-backward backward electron emission anisotropy is observed when ionization takes place at large internuclear distance.