title: Formation and properties of selenium double-helices inside double-wall carbon nanotubes: experiment and theory.
abstract: We report the production of covalently bonded selenium double-helices within the narrow cavity inside double-wall carbon nanotubes. The double-helix structure, characterized by high-resolution transmission electron microscopy and X-ray diffraction, is completely different from the bulk atomic arrangement and may be considered a new structural phase of Se. Supporting ab initio calculations indicate that the observed encapsulated Se double-helices are radially compressed and have formed from free Se atoms or short chains contained inside carbon nanotubes. The calculated electronic structure of Se double-helices is very different from the bulk system, indicating the possibility to develop a new branch of Se chemistry.
authors.affiliation: Research Center for Exotic Nanocarbons (JST), Shinshu University, 4-17-1 Wakasato, Nagano-city 380-8553, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Fujimori
authors.forename: Renato Batista
authors.initials: RB
authors.lastname: dos Santos
authors.forename: Takuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Morinobu
authors.initials: M
authors.lastname: Endo
authors.forename: Katsumi
authors.initials: K
authors.lastname: Kaneko
authors.forename: David
authors.initials: D
authors.lastname: Tománek