Photoelectron and photoion study of the valence photoionization of C60

Abstract Recent photoion yield measurements, done in the valence photoionization region of C 60 , reveal a high fraction of doubly and even triply charged ions [see A. Reinkoster, S. Korica, G. Prumper, J. Viefhaus, K. Godehusen, O. Schwarzkopf, M. Mast, U. Becker, J. Phys. B: At. Mol. Opt. Phys. 37 (2004) 2135]. The C 60 2 + intensity increases continously up to h ν ≈ 60  eV and stays constants at higher photon energies. Moreover, the fragmentation into C 58 + and C 56 + is pronounced in the energy region h ν ≈ 50 –70 eV. The question arises, if after electrons are removed from certain electronic levels, the multiple-ionization or even the fragmentation is somehow triggered. Or in other words, if the multiple-ionization or the fragmentation characteristics can be already seen in the simple (non-coincident) electron data. We can answer the question with the help of such non-coincident valence electron measurements, recorded in the interesting photon energy region h ν ≈ 40 –70 eV.