Photodissociation Quantum Dynamics of the Ar−HF(v = 0) Cluster

Abstract

The ultraviolet photodissociation of Ar−HF(v = 0) is studied by means of wave packet simulations. Photolysis is simulated from two different cluster initial states, namely, the ground and an excited van der Waals (vdW) state, associated with the Ar−H−X and Ar−X−H isomers, respectively. The photolysis dynamics involves mainly direct dissociation of the hydrogen atom, and at most a couple of subsequent collisions of the recoiling H with Ar and F, for the two cluster initial states. The H/Ar collision has a relatively high probability in the case of the initial ground vdW state, while it is much more unlikely for photolysis from the initial excited vdW state. The probability of Ar−F radical products is calculated for several excitation energies along the range of the Ar−HF(v = 0) absorption spectrum. A negligible probability of these products is found for the two cluster initial states, for all the energies studied. The result is attributed to the large amount of energy available for the Ar−F fragment, at the excitation energies contained in the Ar−HF(v = 0) absorption spectrum, which diminishes dramatically the Ar−F survival probability. By comparison of the present results with previous ones on Ar−HX (X = Cl, Br) photolysis, some trends on the photodissociation behavior of this family of clusters are discussed.