PHOTOIONIZATION FRAGMENTATION OF ENDOHEDRAL FULLERENES/

Photoionization/fragmentation of endohedral fullerenes was investigate d by use of laser-desorption time-of-flight (LD-TOF) mass spectroscopy . The velocity distribution of the parent ion (LaC82+) was found to be bimodal, as has previously been shown for laser desorbed C-60(+). The fragment ions have velocity distributions corresponding predominantly to the fast parent ion distribution. The LD-TOF mass spectra taken wi th a relatively low laser fluence were independent of the delay time o f the extraction pulse, showing only a monotonically decreasing patter n of LaC:, (as n decreased). However, with higher laser fluence, it wa s shown that the mass distributions drastically changed from the monot onically decreasing pattern to that of C-2n(+) and LaC:, with magic nu mbers. Based on these findings, a plausible photoionization/fragmentat ion mechanism is presented and discussed.