ROVIBRATIONAL MOTION OF CO IN SOLID C-60

Solid C-60 can be intercalated with CO gas in a 1:1 ratio. The rovibra tional motion of CO in these samples is studied as a function of tempe rature by IR and NMR spectroscopy. The observed spectra indicate a gra dual transition from nearly free motion of CO at room temperature to h indered motion at low temperature, with only tunneling between symmetr y equivalent orientations remaining. The observations are augmented by theory, and details on the local environment of the CO molecules are extracted.