title: A one-dimensional ice structure built from pentagons.
abstract: Heterogeneous ice nucleation has a key role in fields as diverse as atmospheric chemistry and biology. Ice nucleation on metal surfaces affords an opportunity to watch this process unfold at the molecular scale on a well-defined, planar interface. A common feature of structural models for such films is that they are built from hexagonal arrangements of molecules. Here we show, through a combination of scanning tunnelling microscopy, infrared spectroscopy and density-functional theory, that about 1-nm-wide ice chains that nucleate on Cu(110) are not built from hexagons, but instead are built from a face-sharing arrangement of water pentagons. The pentagon structure is favoured over others because it maximizes the water-metal bonding while maintaining a strong hydrogen-bonding network. It reveals an unanticipated structural adaptability of water-ice films, demonstrating that the presence of the substrate can be sufficient to favour non-hexagonal structural units.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
authors.forename: Javier
authors.initials: J
authors.lastname: Carrasco
authors.forename: Angelos
authors.initials: A
authors.lastname: Michaelides
authors.forename: Matthew
authors.initials: M
authors.lastname: Forster
authors.forename: Sam
authors.initials: S
authors.lastname: Haq
authors.forename: Rasmita
authors.initials: R
authors.lastname: Raval
authors.forename: Andrew
authors.initials: A
authors.lastname: Hodgson
mesh_terms: D003300:Copper / Q000737:chemistry*; D007053:Ice; D016252:Microscopy, Scanning Tunneling; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared
chemical_list: D007053:Ice; D003300:Copper