title: Interactions between C and Cu atoms in single-layer graphene: direct observation and modelling.
abstract: Metal doping into the graphene lattice has been studied recently to develop novel nanoelectronic devices and to gain an understanding of the catalytic activities of metals in nanocarbon structures. Here we report the direct observation of interactions between Cu atoms and single-layer graphene by transmission electron microscopy. We document stable configurations of Cu atoms in the graphene sheet and unique transformations of graphene promoted by Cu atoms. First-principles calculations based on density functional theory reveal a reduction of energy barrier that caused rotation of C-C bonds near Cu atoms. We discuss two driving forces, electron irradiation and in situ heating, and conclude that the observed transformations were mainly promoted by electron irradiation. Our results suggest that individual Cu atoms can promote reconstruction of single-layer graphene.
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8573, Japan. KANOU.Emi@nims.go.jp and Surface Physics and Structure Unit, National Institute for Materials Science, Tsukuba, 305-0047, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Kano
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8573, Japan. KANOU.Emi@nims.go.jp and Surface Physics and Structure Unit, National Institute for Materials Science, Tsukuba, 305-0047, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Hashimoto
authors.affiliation: Computational Materials Science Unit, National Institute for Materials Science, Tsukuba, 305-0044, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Kaneko
authors.affiliation: Computational Materials Science Unit, National Institute for Materials Science, Tsukuba, 305-0044, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tajima
authors.affiliation: Computational Materials Science Unit, National Institute for Materials Science, Tsukuba, 305-0044, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Ohno
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8573, Japan. KANOU.Emi@nims.go.jp and Surface Physics and Structure Unit, National Institute for Materials Science, Tsukuba, 305-0047, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Takeguchi