Statistical evaporation of rotating clusters. II. Angular momentum distribution

The change in the angular momentum of an atomic cluster following evaporation is investigated using rigorous phase space theory (PST) and molecular dynamics simulations, with an aim at the possible rotational cooling and heating effects. Influences of the shape of the interaction potential, anharmonicity of the vibrational density of states (DOS), and the initial distribution of excitation energies are systematically studied in the example of the Lennard-Jones cluster LJ14. For this system, the predictions of PST are in quantitative agreement with the results of the simulations, provided the correct forms for the vibrational density of states and the interaction potential are used. The harmonic approximation to the DOS is used to obtain explicit forms for the angular momentum distribution in larger clusters. These are seen to undergo preferential cooling when thermally excited and preferential heating when subject to a strong vibrational excitation.