Abstract: The photofragmentation of C₆₀ fullerene by an ultrafast laser pulse was studied by semiclassical molecular dynamics simulation. Two different laser pulses were used for this study: one with a duration of 40 fs FWHM (full width at half maximum) and the other with a duration of 500 fs FWHM. Both laser pulses had an energy of 2.0 eV. The simulation was run at different laser intensities for each laser pulse. The simulation results showed that a dominant amount of laser energy deposited to C₆₀ fullerene was distributed into electronic energy. From the simulation we find that the electronic excitation from the occupied molecular orbitals to the unoccupied orbitals is closely related to the photofragmentation of C₆₀ fullerene. By analyzing the fragmentation size distribution, the atomic equivalence index, the temperature, and the absorbed energy (including the electronic energy, the potential energy, and the kinetic energy), we found that non-thermal effects play a significant role in the laser fragmentation of C₆₀ fullerene. By examining the fragmentation features of C₆₀ fullerene with two different laser pulses we found that the laser pulse duration affects the fragmentation process significantly and that laser intensity has little effect on the fragmentation after the absorbed electronic energy becomes saturated.

Key words: Laser induced chemical reaction, Fullerene, Photofragmentation, Semiclassical molecular dynamics