Dissociative photodetachment studies of I2-.Ar: coincident imaging of two- and three-body product channels.

Van der Waals clusters serve as prototypical systems for studying processes of energy transfer. The I 2 ·Ar system has attracted particular interest due to the wide array of decay processes occurring in competition with one another. Here, we present systematic dissociative photodetachment (DPD) studies of the I 2 - and I 2 - ·Ar anions in the region 4.24-4.78 eV. The resulting neutral fragments are detected by time- and position-sensitive (TPS) coincident imaging. Photofragment mass distributions and translational energy distributions from the DPD of I 2 - are presented and facilitate understanding of the I 2 ·Ar system. For the I 2 ·Ar complex, channels resulting from two-body dissociation leading to I 2 + Ar photoproducts are observed at all photon energies employed. We also report the first direct observation of the previously inferred three-body dissociation channel leading to I + I + Ar photoproducts. The relative intensities of each decay channel are investigated in relation to the electronic state being accessed. Translational energy distributions of the I 2 ·Ar complex lend further insight into the decay mechanism for each channel.