Simultaneous imaging of both product ions: exploring gateway states for HCl as a benchmark molecule
Simultaneous imaging of both positive and negative product ions is used to exclusively study photoion pair formation free from interference of competing fragmentation channels. Resonance enhanced multi-photon excitation allows us to interrogate potential energy surfaces for vastly differing molecular geometries. 3D imaging provides complete fragment information. We applied the technique to HCl as a benchmark and identified the gateway state leading to photoion pairs. The approach can easily be applied to any molecule exhibiting a potential with an attractive part at large internuclear distances.