title: Impurity decoration for crystal shape control: C60 on Ag(111).
abstract: The decoration of hexagonal Ag/Ag(111) monolayer islands by chains of C60, observed via STM at 300 K, dramatically changes the nanocrystalline shape and fluctuations of the islands. We tune coverage so that a single chain of C60 fully decorates each Ag island boundary, forming a closed circular "necklace." We model the C60-induced rounding in terms of competing energetic and entropic effects. We thereby characterize the decorated-step fluctuations and estimate the C60-Ag and C60-C60 attractions to be approximately 0.13 and approximately 0.03 eV, respectively. Generalizations of our model show that decorating molecules of both circular and rectangular surface-projected symmetry will similarly lower the energy of fully kinked boundaries, leading to corner rounding and reorientations by 30 degrees on (111) surfaces and 45 degrees on (100) surfaces.
authors.affiliation: Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Stasevich
authors.forename: Chenggang
authors.initials: C
authors.lastname: Tao
authors.forename: William G
authors.initials: WG
authors.lastname: Cullen
authors.forename: Ellen D
authors.initials: ED
authors.lastname: Williams
authors.forename: T L
authors.initials: TL
authors.lastname: Einstein