Multiphoton-multiplasmon Excitation Of C/sub60/

Time-of-flight mass spectrometry is used to study the interaction of free C60 molecules with ultrashort high power Ti:sapphire laser pulses. Ionization and fragmentation of C60 by ultrashort high-intensity laser pulses occur predominantly via plasmon excitation. Single and double excitation of collective charge oscillation is observed by remarkably large number of photons. The difference between apparent threshold energies for each ionization or fragmentation and the much lower ionization potentials is a natural consequence of primary excitation process.