Electron and ion angular distributions in resonant dissociative photoionization of H2 and D2 using linearly polarized light

Abstract

We have evaluated fully differential electron angular distributions in H2 and D2 dissociative photoionization by using linearly polarized light of 20, 27 and 33 eV. At 20 eV, the distributions exhibit simple p-wave patterns, which is the signature of direct ionization through the X2Σg+(1sσg) channel. At 27 eV, where the Q1 autoionizing states are populated, we observe a similar pattern, except when the molecule is oriented perpendicularly to the polarization direction and the energy of the ejected electron is small. In contrast, at 33 eV, autoionization from the Q1 and Q2 states leads to interferences between the X2Σg+(1sσg) and 2Σu+(2pσu) ionization channels that result in a strong asymmetry of the electron angular distributions along the molecular axis. This asymmetry changes rapidly with the energy of the ejected electron. Electron angular distributions integrated over all possible molecular orientations or ion angular distributions integrated over electron emission angle show no reminiscence of the above phenomena, but the corresponding asymmetry parameters dramatically change with electron and ion energies in the region of autoionizing states.