Theoretical calculations of XeF ground state kinetics

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Rate coefficients were calculated for collision-induced vibrational and rotational relaxation and for dissociation processes that occur when He atoms collide with XeF(v, J) ground state molecules. These coefficients were calculated using a pairwise additive potential energy surface, which consists of a Morse function for the XeF interaction and Lennard-Jones functions for the HeXe and HeF interactions. It is found that the relaxation and dissociation processes occur by multiquanta (v,J) transitions and that dissociation is greatly enhanced if the total internal energy of the XeF molecule is near the rotationless dissociation limit of XeF. Dissociation can be achieved with either an initial high rotational quantum number and an initial low vibrational quantum number or vice versa. The effectiveness of initial energy in promoting dissociation increases in the order translation–rotation–vibration. Both the temperature and v dependences of the rate coefficients were calculated for collision-induced vibrational and rotational relaxation and dissociation. Strong vibration–rotation coupling in both vibrational relaxation and in the dissociation processes is demonstrated.