Molecular Dynamics Simulations of Noble Gas Release from Endohedral Fullerene Aggregates Due to Cage Disintegration

We report the results of molecular dynamics simulations of the release of five species of noble gas atoms trapped inside a small aggregate of fullerenes in the temperature range 4000 K <= T <= 5000 K. We find that larger noble gas atoms are generally released at a slower rate and that helium is released considerably more rapidly than any of the other noble gases. The differing release rates are due not only to the differences in the size and mass of a given endohedral species but also because larger trapped atoms tend to stabilize the fullerene cage against thermal fluctuations. Unlike the case of atoms entering fullerenes, we find that any atom escaping from the cage results in a window which does not close. Escape rate constants are reported and comparisons with experiment are discussed.