Journal of Physical Chemistry, Vol.99, No.42, 15488-15496, 1995
Elaboration of an Impulsive Model for Collision-Induced Dissociation - Application to Cs2++ar-)S++cs+ar
The crossed-beam method provides uniquely valuable information for deducing details of energy transfer, reaction mechanisms, and broad features of energy disposal in chemical reactions. This crossed-beam study of the dynamics of elastic scattering of CS2+ and the lowest energy dissociation channel. CS2+(X(2)II(g)) --> S+(S-4(u)) + CS(X(1) Sigma(+)) on collision with argon at 17.8 eV collision energy provided the impetus for developing a "knockout" model for collision-induced dissociation. The occurrence of a ridge of intensity of S+ originating within and extending outside the elastic scattering circle is quantitatively rationalized by this model. Symmetry of the scattering ridge about a point on the relative velocity vector and the radius of the ridge which connects maxima in relative intensity ranging from zero scattering angle to 44 degrees (LAB) are quantitatively connected by the model to the bond dissociation energy of CS2+. The model requires that the potential curve describing the interaction of S+ and CS be essentially "flat" when the momentum exchange collision with Ar occurs. Consequently, we infer that transfer of kinetic energy into internal energy of CS2+ equal to its bond dissociation energy occurs in the approach trajectory. It is suggested that this involves the electronic excitation CS2+(X(2)II(g)) --> CS2+(B-2 Sigma(u)(+)).