Photoionization and Fragmentation Dynamics ofC60

Photoionization of ${\mathrm{C}}_{60}$ by 15 ns laser pulses at 193 and 308 nm and by ca. 100 fs pulses at 310 and 620 nm has been studied with reflectron time-of-flight mass spectrometry. The initial fragmentation process is seen to be the ejection of ${C}_{n}$, $n>2$, as opposed to successive ${\mathrm{C}}_{2}$ evaporation. The fragment ions produced in this initial fragmentation step have sufficient internal energy to cool, by the emission of a ${\mathrm{C}}_{2}$ molecule in the field-free region of the mass spectrometer. Pump-probe experiments with 90 fs laser pulses at 620 nm give additional insights into the ionization mechanism.