ON THE SECONDARY IONIC EMISSION OF POLYATOMIC IONS FROM C-60 SAMPLES

We present secondary ion mass spectrometry experiments on a C60 sample bombarded with a Cs+ primary beam. The obtained spectrum exhibits an odd-even alternation of the C(n) intensities with even n species favou red. This alternation is not so regular as for graphite samples. We gi ve a qualitative explanation of the difference between the C60 and the graphite samples by using the Radi results on the photonic fragmentat ion of C(n)+ clusters in the gas phase and also by taking into account the electron-affinities of C(n) clusters which, in the n less-than-or -equal-to 10 range, are larger for even n. We then introduce a theoret ical model allowing the calculation of C(n), C+ and C(n)- properties ( n less than or similar to 60). Preliminary results on the cohesive ene rgy, the electron-affinity and the ionization potential of C3 and C60 are given.