PHOTOLYSIS OF HCL IN THE AR2-HCL AND AR-HCL CLUSTERS - THE CLUSTER-SIZE EFFECT

The photodissociation dynamics of HCl in the clusters Ar2-HCl and Ar-H Cl is studied in order to explore the cluster size effect. A quasi cla ssical trajectory approach is employ to simulate the photofragmentatio n dynamics. interesting manifestations of the cage effect are found in the light and the heavy atom kinetic energy distributions, with impor tant differences between the two clusters. The Ar and Cl distributions provide separate information on dynamical events which cannot be reso lved in the hydrogen distribution. Only two different excitation wavel engths are used in the simulations. The cage effect is found to be str ongly dependent on the wavelength employed to excite the HCl molecule. This is so to the extent that the trend of an increasing cage effect with the cluster size is reversed for the smaller wavelength. New type s of resonance behavior are observed for the hydrogen motion in Ar2-HC l compared with the Ar-HCl cluster. An interesting difference between Ar-HCl and Ar2-HCl is that, in the latter case, Ar2 can form as produc t of the photodissociation, with a high yield for the two wavelengths. The dynamics of the process and the implications of the results are d iscussed.