MOLECULAR-DYNAMICS SIMULATIONS AND EXPERIMENTAL STUDIES OF THE FORMATION OF ENDOHEDRAL COMPLEXES OF BUCKMINSTERFULLERENE

The formation of endohedral C60He+ complexes in mass spectrometric experiments in which C60+ collides with He at kiloelectronvolt energies has been modeled with molecular dynamics simulations. Experimental results have shown that the collision energy at which the greatest abundance of C60He+ is observed is 5000 eV, while molecular dynamics simulations predict that optimal complex formation should occur in 8000-eV collisions. When the effects of the experimentally observed unimolecular decomposition of the internally excited C60He+ complex are considered, however, there is relatively good agreement between the predictions of the simulations and the experimental results. The simulations provide a detailed picture of the trapping process and show that low-energy collisions with low impact parameters and high-energy collisions with high impact parameters are most likely to result in formation of C60He+. The molecular dynamics simulations also provide insight into inelastic scattering processes observed in the mass spectrometric experiments; the results are consistent with an impulsive collision in which momentum transfer occurs between He and an isolated portion of C60+, as predicted by the simulations.