INTERMOLECULAR COUPLING OF MONOLAYER C-60

Raman spectra of ultrathin C-60 films on SiOx (x approximate to 2) in ultra high vacuum show strong irradiation induced changes which persis t but decay with time (2-3hours). The induced changes are suppressed u pon cooling (120 K) and additional changes are introduced with heating (600 K). The observation of induced low energy vibrational bands betw een the molecular and lattice vibrational spectrum suggests the format ion of covalent bonds between C-60 molecules. The short range intermol ecular coupling has been estimated by applying the semi-empirical inte ratomic Tersoff potential.