Photoelectron and photoion study of the valence photoionization of C 60
Recent photoion yield measurements, done in the valence photoionization region of C60, reveal a high fraction of doubly and even triply charged ions [see A. Reinköster, S. Korica, G. Prümper, J. Viefhaus, K. Godehusen, O. Schwarzkopf, M. Mast, U. Becker, J. Phys. B: At. Mol. Opt. Phys. 37 (2004) 2135]. The C602+ intensity increases continously up to hν≈60 eV and stays constants at higher photon energies. Moreover, the fragmentation into C58+ and C56+ is pronounced in the energy region hν≈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 hν≈40–70 eV.