Li_nC₆₀⁺ Cluster Formation

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        Li_nC₆₀⁺ clusters formed sequentially from the collisions of Li atoms with C₆₀⁺ ions. The mass spectra of  Li_nC₆₀⁺ clusters for different Li flux exposure times was obtained by resonant ejection. These data were taken at 1.5x10^-3 Torr He pressure and a trap temperature of 80 K. (Cluster formation is not observed for trap temperatures >170 K.) As the exposure time is increased, the C₆₀⁺ ion concentration decreased as the cluster spectrum broadened and moved to higher masses. Clusters up to n=14 are observed at an exposure of 10 sec from an initial ~2000 C₆₀⁺ ions. Indicated ion numbers were derived from integrating the electron multiplier data for each mass peak.