Dissociation dynamics of vibrationally excited van der Waals clusters: I2XY → I2+X+Y (X, Y=He, Ne)

Publisher Website
Google Scholar
Abstract
The dynamics of sequential dissociation processes of the type XI2(v)Y → X+I2(v′)Y → X+Y+I2(v″) (X,Y=Ne, He) are studied using classical trajectory calculations and a recently presented classical version of the time‐dependent self‐consistent field (TDSCF) method. The results obtained indicate the presence of significant dynamical correlation effects of the rare‐gas atoms on each other despite the negligible direct interaction between them; this is in qualitative agreement with experimental findings. Good agreement is found for the rate constants and the variation with rare gas as well as the branching ratios (NeI2He → NeI2+He vs → I2He+Ne) calculated from TDSCF and from classical trajectories. Both classical trajectories and TDSCF show an essentially impulsive dissociation mechanism, in which dissociation typically follows a considerable number of vibrations, and is due to a relatively rare internal hard collision between an I atom and the rare gas. As in the three‐body I2X case, this mechanism differs from that in the RRKM strong coupling model. Energy‐ and momentum‐gap relations, based on the weak‐coupling picture, are found to be relatively successful but fail to describe the dynamics quantitatively.