Detailed dynamics of three-body recombination of ions in central collisions

The potential energy surface describing quantitatively the dynamics of the collision induced dissociation reactions CsBr + Xe → Cs+ + Br− + Xe, CsXe+ + Br− is used to explore detailed dynamics of the reverse process of direct three-body recombination of the Cs+ and Br− ions undergoing a central collision. For a stepwise analysis of the course of the elementary process, visualization of the trajectory and of the energy state of each pair of the particles is employed. Several different mechanisms of the reaction are found. Their occurrence depends on the impact parameter of the collision of the third body with the recombining pair and on the angles determining the spatial orientation of the ion velocities. The major role in stabilization of the recombination products is played by the repulsion potentials between the ions and the third body, but the amount of energy transferred depends not only on the repulsion interaction strength. Recombination is shown to be able to happen for very low energies of repulsion between the third body and the ions and even in the complete absence of repulsion. In all the cases, the particular recombination mechanism is determined by the dynamical features of the collision. The relation between the kinematic parameters of a collision of the three particles and the recombination mechanism is considered.

A fragment of a trajectory for the Cs+ + Br− + Xe → CsBr + Xe reaction (a product of the visualization program). The collection of data shown is of the same type as in Fig. 2.Highlights► We study direct recombination of Cs cation and Br anion in the presence of Xe. ► Quasiclassical trajectory method is used with visualizing individual trajectories. ► Several different dynamical mechanisms of recombination are revealed. ► The major role in CsBr stabilization is played by repulsion between the ions and Xe. ► Recombination can however occur in the absence of repulsion.