Dynamics of excited rare-gas atoms with halide molecules: the Ar(P-3)+ClF -> ArCl*+F, ArF*+Cl reaction

The product species originating from the interaction between metastable Ar atoms and the CIF molecules were studied using theoretical (structure and d ynamics) methods. Quasiclassical trajectory calculations were carried out o n an analytical, monovalued potential energy surface. The energy surface wa s obtained by means of a fit to CTS (UHF) ab initio points calculated for a set of relevant triatomic configurations, adequately connected to assume t hat the reaction takes place adiabatically. Cross sections, rate constants, and products' energy disposal for both ArCl* and ArF* excimer formation we re calculated, showing a dominancy of the less stable ArCl* + F channel. In addition, angular distributions and rotational alignments for both product channels were analyzed. The influence of reactant internal excitation on i ntegral cross sections and product energy distributions was also studied, c onsidering a wide range of initial rovibrational levels. A remarkable enhan cing effect of the reactant rotation was found, as compared to vibration, f or the ArCl* product, whereas the opposite trend is observed for the ArF* c hannel. Whenever possible, the observed behavior was related to both HHL an d HLH kinematical considerations. The effect of rotational excitation was u sed as well to elucidate the angular momentum transfer mechanism among the two competing reaction channels. The role of a relevant rotation-orbiting c oupling was identified. Results are found to be, overall, in agreement with the available experimental information, for the title reaction as well as other related systems. This indicates that the fundamental assumption of th e present work, namely that the reaction proceeds on a single excited adiab atic potential surface, is accurate enough to account for the main trends o f the reaction dynamics.