Sympathetic cooling of fullerene ions by laser-cooledMg+ions in a linear rf trap

Abstract

A large sample (N{approx_equal}10{sup 4}) of fullerene ions (m=720 a.u) is cooled by means of a much smaller number({approx_equal}100) of laser-cooled magnesium ions (m=24 a.u). The results demonstrate that sympathetic cooling of large molecules to low temperatures is feasible. The temperature of the {sup 24}Mg{sup +} ions in the mixed Mg{sup +}-C{sub 60}{sup +} ion cloud stored in an rf trap is found to be T{sub Mg}=5 K from their fluorescence signal. Molecular dynamics simulations are used to obtain the corresponding equilibrium temperature of the fullerene ions, and show that T{sub C{sub 60}}=14 K.