ON THE INFLUENCE OF COLLISION MASS AND INTERACTION POTENTIAL TO THE ENERGY-TRANSFER IN SMALL THERMAL GAS-PHASE CLUSTERS

We have studied the collisional energy transfer, and the sticking prob ability, between molybdenum clusters and the rare-gas atoms Ne, Ar, an d Xe. We have chosen these systems as nontrivial models of the thermal ization process of metal clusters in a background gas. The mean energy transfer cross sections and the energy transfer rate constants, and t he sticking probability of molybdenum clusters (Mo-4, Mo-9, Mo-14) wit h rare-gas atoms are computed as functions of relative collision energ y (gas temperature) and reduced mass. The dynamics of gas phase molybd enum clusters are simulated by molecular dynamics trajectories whose i nitial conditions are sampled from a distribution appropriate to therm al collisions. The simulation shows that the energy transfer rate cons tants are dominated by the collision frequency. The mean energy transf er cross sections are coupled to the collision mass as well as to the actual interaction force. The coupling is nonlinear, and there is some evidence that in the energy transfer, for small clusters, complex col lisions are involved. The sticking probability at equilibrium temperat ure is far below 1.