title: Rotor in a cage: Infrared spectroscopy of an endohedral hydrogen-fullerene complex.
abstract: We report the observation of quantized translational and rotational motion of molecular hydrogen inside the cages of C(60). Narrow infrared absorption lines at the temperature of 6 K correspond to vibrational excitations in combination with translational and rotational excitations and show well-resolved splittings due to the coupling between translational and rotational modes of the endohedral H(2) molecule. A theoretical model shows that H(2) inside C(60) is a three-dimensional quantum rotor moving in a nearly spherical potential. The theory provides both the frequencies and the intensities of the observed infrared transitions. Good agreement with the experimental results is obtained by fitting a small number of empirical parameters to describe the confining potential, as well as the relative concentration of ortho- and para-H(2).
authors.affiliation: School of Chemistry, Southampton University, Southampton SO17 1BJ, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Mamone
authors.forename: Min
authors.initials: M
authors.lastname: Ge
authors.forename: D
authors.initials: D
authors.lastname: Hüvonen
authors.forename: U
authors.initials: U
authors.lastname: Nagel
authors.forename: A
authors.initials: A
authors.lastname: Danquigny
authors.forename: F
authors.initials: F
authors.lastname: Cuda
authors.forename: M C
authors.initials: MC
authors.lastname: Grossel
authors.forename: Y
authors.initials: Y
authors.lastname: Murata
authors.forename: K
authors.initials: K
authors.lastname: Komatsu
authors.forename: M H
authors.initials: MH
authors.lastname: Levitt
authors.forename: T
authors.initials: T
authors.lastname: Rõõm
authors.forename: M
authors.initials: M
authors.lastname: Carravetta