Insertion of Xe and Kr Atoms into $C_{60}$ and $C_{70}$ Fullerenes and the Formation of Dimers

The radioactive endohedral fullerenes ${}^{127}\mathrm{Xe}@{\mathrm{C}}_{60}$, ${}^{127}\mathrm{Xe}@{\mathrm{C}}_{70}$, ${}^{79}\mathrm{Kr}@{\mathrm{C}}_{60}$, and ${}^{79}\mathrm{Kr}@{\mathrm{C}}_{70}$, and their dimers, are detected using radiochemical and radiochromatographic techniques in the final solution of samples in which Xe or Kr has penetrated into ${\mathrm{C}}_{60}$ or ${\mathrm{C}}_{70}$ by a nuclear reaction recoil process. Carrying out ab initio molecular dynamics simulations based on an all-electron mixed basis approach, we confirmed that the insertion of Xe and Kr atoms into ${\mathrm{C}}_{60}$ through six-membered rings is possible in a certain range of the kinetic energy: 130–200 eV for Xe and 80–150 eV for Kr.