Nanosecond simulations of the dynamics of C60 excited by intense near-infrared laser pulses: Impulsive Raman excitation, rearrangement, and fragmentation

Impulsive Raman excitation of C60 by single or double pulses of near-infrared wavelength λ = 1800 nm was investigated by using a time-dependent adiabatic state approach combined with the density functional theory method. We confirmed that the vibrational energy stored in a Raman active mode of C60 is maximized when Tp ∼ Tvib/2 in the case of a single pulse, where Tp is the pulse length and Tvib is the vibrational period of the mode. In the case of a double pulse, mode selective excitation can be achieved by adjusting the pulse interval τ. The energy of a Raman active mode is maximized if τ is chosen to equal an integer multiple of Tvib and it is minimized if τ is equal to a half-integer multiple of Tvib. We also investigated the subsequent picosecond or nanosecond dynamics of Stone-Wales rearrangement (SWR) and fragmentation by using the density-functional based tight-binding semiempirical method. We present how SWRs are caused by the flow of vibrational kinetic energy on the carbon bond network of C60. I...