Vibrational spectrum ofC60sin the p-tert-butylcalix[8]arene(1:1)C60scomplex

We report the results of Raman, infrared, and inelastic neutron scattering investigations of the vibrational spectrum of the complex p-tert-butylcalix[8]arene(1:1)fullerene, a system with almost isolated ${\mathrm{C}}_{60}$ molecules confined inside neutral cages. All the internal optical-active modes of the ${\mathrm{C}}_{60}$ guest have been identified, and further modes which can be attributed to ${\mathrm{C}}_{60}$ intramolecular vibrations appear in the neutron scattering function. A comparison with the vibrational spectrum of empty p-tert-butylcalix[8]arene indicates that the host-guest interaction is very weak. As solid-state effects are also practically suppressed, the investigated complex gives the unique opportunity to study almost free fullerene balls confined in the solid state.