PHOTOFRAGMENTATION OF C-60 IN SEEDED SUPERSONIC MOLECULAR-BEAMS - EFFECTS OF RO-VIBRATIONAL COOLING

Experiments in He seeded C-60 supersonic beams show that multiphoton i onization and fragmentation are strongly affected by the initial re-vi brational state of fullerene. The cooling generated by the supersonic expansion induces a higher rate of fragmentation and a significant shi ft of the barycenter of the mass distribution toward smaller fragments . The competition between the different decay channels results to be s trongly affected, Our findings suggest that a purely statistical descr iption, which is commonly assumed, could be inadequate and that proces ses involving the phonon coupling with collective electronic excitatio n play an important role in governing the access to different decay ch annels.