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

A large sample (N approximate to 10(4)) of fullerene ions (m=720 a.u) is cooled by means of a much smaller number(approximate to 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 Mg-24(+) ions in the mixed Mg+-C-60(+) ion cloud stored in an rf trap is found to be T-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-C60=14 K.