ROTATIONAL HEATING AND COOLING DURING THE EVAPORATION OF ATOMS FROM EXCITED CLUSTERS

A model based on phase space theory has been used to examine the effect that multiple fragmentations from excited, weakly bound cluster ions have on the final rotational temperatures of the reaction products. It is predicted that small clusters, such as Ar2+ and Ar3 +, could emerge from a multiple reaction sequence with comparatively high rotational temperatures. In contrast, large clusters, e.g., Ar 40+, experience slight rotational cooling when they undergo ≃ 15 fragmentation steps. In each case, these results can be rationalized in terms of the relative magnitudes of the rotational and orbital angular momenta at each reaction step. Recent experimental observations on cluster ions are discussed in the light of predictions from the model. © 1990 American Institute of Physics.