Highly Charged Clusters of Fullerenes: Charge Mobility and Appearance Sizes

Clusters of fullerenes $({\mathrm{C}}_{60},{\mathrm{C}}_{70}{)}_n$ are produced in a gas aggregation source and are multiply ionized in collisions with highly charged ${\mathrm{X}\mathrm{e}}^{20+,30+}$ ions. Their stabilities and decay processes are analyzed with high-resolution time-of-flight mass spectrometry. Fullerene clusters in charge states up to $q=5$ have been observed and appearance sizes are found to be as small as $n_{\mathrm{a}\mathrm{p}\mathrm{p}}=5$, 10, 21, and 33 for $q=2$, 3, 4, and 5, respectively. The analysis of the multicoincident fragmentation spectra indicates a high charge mobility. This is in contrast to charge localization effects which have been reported for ${\mathrm{A}\mathrm{r}}_n^{q+}$ rare gas clusters. Clusters of fullerenes are found to be conducting when multiply charged.