Photodissociation of Water Dimer at 205 nm

Abstract

A deuterated water dimer, (D 2 O) 2 , absorbs a photon at 205 nm releasing a fragment D atom. The negative angular anisotropy parameters are observed experimentally with photofragment imaging spectroscopy. In this dissociation, one of the translational energy distributions obtained for the fragment D atoms peaks at around 1 kcal mol - 1 , which is much smaller than the maximum available energy, 16.2 kcal mol - 1 . These results suggest an energy loss process of the fragment D atom, which is induced by a collision with the oxygen atom in the dimer before it leaves the parent molecule. A direct ab initio trajectory calculation for the internal collision process of the D atom in the dimer has been performed. The obtained energy loss is in good agreement with the present experimental results.