Controlled Atomic Doping of a Single C 60 Molecule

Abstract
We report a method for controllably attaching an arbitrary number of charge dopant atoms directly to a single, isolated molecule. Charge-donating K atoms adsorbed on a silver surface were reversibly attached to a C 60 molecule by moving it over K atoms with a scanning tunneling microscope tip. Spectroscopic measurements reveal that each attached K atom donates a constant amount of charge (∼0.6 electron charge) to the C 60 host, thereby enabling its molecular electronic structure to be precisely and reversibly tuned.