Nanosecond and picosecond laser desorption of C_60

摘要

Laser desorption of C_60 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 C_60~+ 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 iwth ps pulses, cannot be produced y a purely thermal mechanism. Different mechanisms are postulated for the production of the fast components in the two cases.