Benzene confinement in single-walled carbon nanotubes: inelastic and quasielastic neutron scattering

We characterize experimentally the dynamical properties of benzene confined in single-walled carbon nanotubes (SWNT) of diameter 14 {\AA}. The presence of benzene inside the nanotubes is demonstrated by measuring the small-angle neutron scattering intensities from a properly prepared C$_{6}$D$_{6}$ benzene -- SWNT sample. The incoherent inelastic neutron scattering spectra from C$_{6}$H$_{6}$ benzene in the nanotubes and in the bulk crystal are measured at 4 K, up to an energy transfer of 130 meV. The effective vibrational density of states reveals a significant redistribution of all intermolecular modes for the confined benzene, whereas the intramolecular modes are nearly unaffected. Incoherent quasielastic neutron scattering spectra from C$_{6}$H$_{6}$ benzene in the nanotubes were also collected from 9 K to room temperature, at an energy-transfer resolution of approx. 80$\mu $eV. The orientational and translational diffusive dynamics of confined benzene are discussed on the basis of these data.