Gordon Research Conference Poster
C60+ Reactions with Alkali Metals in an rf Trap
Douglas Cameron, Mordechai Rokni, and Joel
Rowland Institute for Science, Cambridge, Massachusetts 02142-1297
Ion-neutral interactions between alkali atoms and a trapped cloud of C60+ ions was studied in an rf Paul trap. The ion cloud temperature was maintained at ~80K by collisions with a dilute He background gas. Dissociative charge-exchange was measured for Na, K, Rb and Cs with alkali-C60+ collision energies of ~60 to 120 meV set by the alkali atom velocity. At temperatures below ~170K, the growth of LinC60+ clusters (n=1-18) occurs by the sequential association of Li atoms. Charge-exchange rates are derived from measurements of the time decay of C60+ ions. In the unique case of LiC60+, pressure dependence of formation displays a competition between vibrational relaxation by He collisions and unimolecular dissociation. Rate equation analysis provides a measurement of the Li binding energy and the rate of vibrational relaxation. For all other cases, LinC60+ n>1, cluster formation occurs with negligible dissociative loss.
1. Experimental Configuration 2. Dissociative Charge-Exchange 3. LinC60+ Cluster Formation 4. LinC60+ Formation after Selection 5. Lithium Flux Pressure Dependence 6. Uniform Reaction Rates 7. No Dissociation of LinC60+ for n>1 8. LinC60+ Formation Rate Equations 9. A Kinetic Model of LiC60+ Formation Pressure Dependence 10. Charge Exchange Rates 11. Summary
Reactions with Alkali Metals in an rf Trap