Negative carbon cluster ion beams: New evidence for the special nature of C60

Abstract Cold carbon cluster negative ions are formed by supersonic expansion of a plasma created at the nozzle of a supersonic cluster beam source by an excimer laser pulse. The observed distribution of mass peaks for the C − n ions for n > 40 demon- strates that the evidence previously given for the special stability of neutral C 60 and the existence of spheroidal carbon shells cannot be an artifact of the ionization conditions.