Gas-phase photodissociation of AuCH2+: the dissociation threshold of jet-cooled and rotationally thermalized ions

The photofragment spectra of jet-cooled and rotationally thermalized AuCH2+ are reported. Two channels are observed: loss of H2 and loss of CH2 with a branching ratio of 1.4:1 over the region studied. The presence of a threshold at 322 nm for the dissociation of jet-cooled AuCH2+ to Au++CH2 implies the upper limit D0o(Au+–CH2)≤372±3 kJ mol−1. The dissociation threshold of ions rotationally thermalized in an ion trap shifts to lower energy by the amount of parent rotational energy.