Molecular frame photoelectron angular distributions in dissociative photoionization ofH2 in theregion of the Q1 and Q2 doubly excited states

Abstract

Dissociative photoionization ofH2 induced by VUV linearly polarized synchrotron radiationP has been studiedusing the (VH+,Ve,P) vector correlation method. The ion–electron kinetic energy correlationdiagrams obtained for the three photon excitation energieshν = 20, 28.5and 32.5 eV enable us to identify and select the dominant dissociative photoionization processes. TheIχ(θe,ϕe) molecular frame photoelectron angular distributions for any orientationχ of the molecular axis with respect to the polarization are reported for direct photoionization ofH2 into theH2+(2Σg+) ionic groundstate at hν = 20 eVand for the dominant DPI processes involving autoionization of theH2(Q1 1Σu+(1)) andH2(Q2 1Πu(1)) doubly excitedstates into the H2+(2Σg+) and H2+(2Σu+) continua at hν = 28.5 and 32.5 eV. They show the dominant excitation of ap σu partial wave inautoionization of the Q1(1Σu+(1)) state into the H2+(1s σg) ionic stateand that of a d πg partial wavein autoionization of the Q2(1Πu(1)) state into the H2+(2p σu) continuum. A molecular frame forward–backward electron emission anisotropy is observedwhen ionization takes place at large internuclear distance.