Christopher M. Laperle

Picosecond X-ray absorption measurements of the ligand substitution dynamics of Fe(CO)5 in ethanol

Ultrafast X-ray absorption near edge spectroscopy has been carried out for photo excited iron pentacarbonyl in ethanol with 2 picosecond resolution. A temporal resolution limited dissociation process was observed, followed by the formation of the mono-substituted complex Fe(CO)(4)EtOH within a few tens of picoseconds. The measurements have been carried out with a newly developed X-ray absorption instrument at station 7 ID-C of the Advanced Photon Source. The results show that single picosecond temporal resolution can be achieved at a synchrotron beam line.

Experimental probes of transient neutral species using dissociative charge exchange

In this review, recent progress on studies of the dissociation dynamics of transient neutral species produced by charge exchange (CE) of molecular cations with caesium is reviewed. CE experiments using translational spectroscopy in fast ion beams have made important contributions to understanding the spectroscopy and dynamics of high-lying excited states of transient species for some 50 years. Recent advances in time- and position-sensitive detection techniques coupled to jet-cooled supersonic expansion ion sources have allowed measurements yielding unprecedented detail for dissociation processes occurring from complex molecular species. Applications of this technique to studying the two- and three-body dissociation of H3 and sym-triazine, as well as the two-body dissociation of the HN2 radical to H + N2 are reviewed. These systems illustrate the insights gained into the dynamics of the dissociative states from examination of product kinetic energy release distributions and detailed measurements of momentum partitioning in three-body dissociation processes.