Delayed ionization of fullerenes and fullerene derivatives upon laser desorption and surface collision

Delayed electron emission has been observed upon laser desorption for several fullerenes, endohedral metallofullerenes, and large carbon clusters formed by coalescence reactions. Odd-numbered carbon clusters and fullerene derivatives with exohedral functional groups do not show delayed ionization under similar conditions, presumably due to lower dissociation energies. Thus, delayed electron emission is suggested to be a characteristic indicator for strongly bound fullerene structures. Measurements of the rate of delayed electron emission are used together with structural information from other sources to calculate ionization potentials for these species. Selective observation of delayed electron emission from scattered C-60* after surface impact and neutralization of C-60(+) on graphite confirms an earlier report of this process by Whetten et al.(6)