Laser-induced nonthermal fragmentation of C₆₀ studied by semiclassical dynamics simulation

Abstract

Photofragmentation of the C₆₀ fullerene induced by ultrafast laser pulses is studied by semiclassical dynamics simulation. The simulation study is focused on the excitation below the continuum levels. A laser pulse of 40 fs (FWHM) with an effective photon energy of 2.0 eV and different intensities was selected to interact with the C₆₀ fullerene. The simulation results show that averaged fragmentation size distribution over groups of initial geometries selected at random exhibits a power law pattern with the peak at C₂ at high laser pulse intensities. The threshold for the C₆₀ fragmentation was determined. The simulation finds that as many as 55 electrons are excited from the occupied molecular orbitals to unoccupied molecular orbitals upon the laser irradiation and that the number of the fragments significantly depends on the number of electrons excited. Finally, the temperature examination seems to suggest that the nonthermal effect may play a significant role in laser fragmentation of the C₆₀ fullerene.

Keywords:

• nonthermal
• photofragmentation
• semiclassical
• dynamics simulation

Acknowledgments

We thank Roland E. Allen for helpful discussions. This work is supported by the National Natural Science Foundation of China (No. 20773168) and Project of Science Technology Foundation of Chongqing Education Committee (No. KJ070506). Acknowledgment is also made to the donors of The American Chemical Society Petroleum Research Fund for support of this research at Nicholls State University. The Supercomputer Facility at Texas A&M University provided computational assistance.