VELOCITY AND ANGULAR DISTRIBUTIONS OF CATIONS PRODUCED UPON LASER-DESORPTION OF C-60 AND C60OX (X=2-4)

The mechanism of UV laser desorption/ionization of C-60 and C60Ox (x = 2-4) has been studied by measuring the angle and arrival time distrib ution for positive ions generated upon laser irradiation of microcryst alline targets. Observations include evidence for desorption ''jet'' f ormation as well as for on-beam axis enrichment of coalescence product s. These measurements imply that internal and kinetic energy of prompt ly desorbing material are correlated and suggest that coalescence prod ucts such as C-118(+) are generated within the material ablated by one laser pulse rather than from previous photopolymerization. The data a re contrasted to laser desorption measurements of NaI/CsI mixed target s for which near effusive ion velocity distributions are observed.