Nanosecond and picosecond laser desorption of C60

Laser desorption of C60 using nanosecond and picosecond laser pulses has been investigated. The velocity distributions of the desorbed ions were determined by means of time-of-flight mass spectrometry. Optical emission spectroscopy was used to determine the internal energy of the desorbed species. Typically, the C60+ velocity distributions are bimodal, indicative of two distinct desorption mechanisms. The velocities and internal energies of the slow particles are consistent with a purely thermal desorption mechanism. The fast particles, which dominate for desorption with ps pulses, cannot be produced by a purely thermal mechanism. Different mechanisms are postulated for the production of the fast components in the two cases.