title: Quantum Confinement of Surface Electrons by Molecular Nanohoop Corrals.
abstract: Quantum confinement of two-dimensional surface electronic states has been explored as a way for controllably modifying the electronic structures of a variety of coinage metal surfaces. In this Letter, we use scanning tunneling microscopy and spectroscopy (STM/STS) to study the electron confinement within individual ring-shaped cycloparaphenylene (CPP) molecules forming self-assembled films on Ag(111) and Au(111) surfaces. STM imaging and STS mapping show the presence of electronic states localized in the interiors of CPP rings, inconsistent with the expected localization of molecular electronic orbitals. Electronic energies of these states show considerable variations correlated with the molecular shape. These observations are explained by the presence of localized states formed due to confinement of surface electrons by the CPP skeletal framework, which thus acts as a molecular electronic "corral". Our experiments suggest an approach to robust large-area modification of the surface electronic structure via quantum confinement within molecules forming self-assembled layers.
authors.affiliation: Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: Benjamen N
authors.initials: BN
authors.lastname: Taber
authors.affiliation: Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: Christian F
authors.initials: CF
authors.lastname: Gervasi
authors.affiliation: Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: Jon M
authors.initials: JM
authors.lastname: Mills
authors.affiliation: Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Kislitsyn
authors.affiliation: Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: Evan R
authors.initials: ER
authors.lastname: Darzi
authors.affiliation: Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: William G
authors.initials: WG
authors.lastname: Crowley
authors.affiliation: Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Jasti
authors.affiliation: Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States.
authors.forename: George V
authors.initials: GV
authors.lastname: Nazin