Communication: Mass-analyzed velocity map imaging of thermal photofragments from C60

Abstract

The velocity distributions of the fragments produced by dissociative photoionization of C(60) have been measured in the extreme UV region for the first time, by using a flight-time resolved velocity map imaging technique combined with a high-temperature molecular beam and synchrotron radiation. Values of the average kinetic energy release were estimated at six different photon energies with respect to five reaction steps of sequential C(2) ejection, starting from C(60)(2+)-->C(58)(2+)+C(2) to C(52)(2+)-->C(50)(2+)+C(2). The translational temperatures of the fragment ions were found to be lower than those obtained by laser multiphoton absorption of C(60). The kinetic energies released in the first to fourth steps increase with increasing hnu and reach 0.35-0.5 eV at hnu=102 eV, reflecting statistical redistribution of the excess energy in the transition state, whereas that in the fifth step leading to C(50)(2+) was exceptionally small.