The photofragmentation of Ceo fullerene by an ultrafast laser pulse was studied by semi-classical 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 Ceo 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 Ceo 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 Ceo fullerene. By examining the fragmentation features of Ceo 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.%基于半经典分子动力学方法模拟超快激光诱导的C60光裂解反应.选择能量为2.0 eV,半峰全宽(FWHM)分别为40和500 fs的激光作用于C60分子,调节脉冲强度使其发生裂解反应,比较长短脉宽飞秒激光对C60裂解反应机理的影响.通过分析产物分布、原子平衡指数、温度以及吸收能量(包括动能、势能和电子能量),证实飞秒激光脉冲下C60的光裂解主要由电子激发态控制,非热力学效应在该反应中起重要作用.激光场的作用时间和强度均影响光裂解反应过程,而电子吸收能量饱和后光场强度的作用则变得不明显.
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