Intra-molecular H2+ formation in the core-excited HCCH probed by multiple-ion coincidence momentum imaging

Abstract In the HCCH molecule, H 2 + ions have been produced only at the 1s→π * excitation, suggesting that the H 2 + ion formation is mediated by the core excitation. The nuclear motion in the C 1s −1 π * core-excited state is probed using a multiple-ion-coincidence imaging technique and the enhanced cis bending motion is found by examining the H–H correlation angle distributions. The H 2 + formation is thus attributed to the cis bending motion caused in the C 1s −1 π * state.