Hollow ion formation studied by electron spectroscopy of 18O8+-C60 at 4.4 keV/amu

The electron spectrum produced in a low velocity collision between a multicharged ion and a C-60 molecule is measured for the first time. Its structure looks like that of electron spectra measured with heavy atomic targets, but lines coming from the autoionization of doubly-excited states of O6+ ions are superimposed on a much more intense continuous background, strongly peaked at low electron energies. Double capture is found to occur into the 6lnl' (n = 6 to 12) and 7lnl' (n = 7 to 11) Rydberg series. Capture of three and four electrons is also briefly discussed. Help in the identification of the reactions is given by separate energy gain measurements. A time-of-night spectrum of the target ions measured in coincidence with low energy electrons (E-e < 10 eV) shows that the production of these electrons is often accompanied by a C-60 cage destruction.