Gas-phase photodissociation of AuCH+2:: 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 H-2 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 D(0)degrees(Au+-CH2) less than or equal to 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. (C) 2000 Elsevier Science B.V. All rights reserved.