Growth and dynamics of C$_{60}$ molecules on Ag(111)

C$_{60}$ monolayers on Ag(111) form various structures that depend on the surface preparation. For films deposited at 300 K, the monolayer comprises close-packed domains that are incommensurate with the substrate. These domains progressively convert into a commensurate (2$\surd $3x2$\surd $3)R30 structure as the annealing temperature is increased. The annealing process activates the formation of vacancies beneath some of the C$_{60}$ molecules, resulting in a temperature-dependent equilibrium population of about 50{\%} of the molecules sitting on vacancies and 50{\%} sitting on top of Ag atoms in the commensurate phase. In addition to molecules in these two sites, about 0.5{\%} of the molecules image very brightly, and these molecules are in dynamical equilibrium with the other two types. This talk will focus on scanning tunneling microscopy and low-energy diffraction studies of the structure and dynamics of the monolayer phases of C$_{60}$ molecules on Ag(111).