Dynamics of desorption of reaction products from reactions on large clusters

Abstract

The reaction of barium trimers with molecules of SF₆ has been investigated on large argon clusters (around 4000 atoms). The reaction is strongly exoergic (by approximately 5 eV) and leads to several reaction products; among which, the desorption of ground state BaF molecules is observed. The energetics of these molecules has been analysed by laser-induced fluorescence with subDoppler resolution. The rotational, vibrational and translational energy distributions are found to be thermal, with temperatures in the range 1600–2400 K. These temperatures are lower than those found in a preceding analysis of chemiluminescent desorbed products but remain much higher than the temperature of the cluster. This is interpreted by different time scales of interaction of the products with the cluster substrate: short times leading to highly internally excited products, long times to solvated products, with the ground state desorbed products appearing as intermediates in between.