title: Surface-mediated chain reaction through dissociative attachment.
abstract: Chain reactions on a surface offer an important route to linear nanopatterning. We recently reported cooperative reactions on a silicon surface in which the reaction of one halogen atom with a silicon atom of a silicon dimer induced the halogenation of its neighbouring silicon atom through surface-mediated charge transfer. The reaction was unable to propagate further but here we describe how, by chemically bridging the gaps between the rows of these silicon dimers, this mechanism is able to form extended chains. The agents for chain growth are CH(3)Cl molecules that dissociatively attach CH(3) groups and chlorine atoms to silicon atoms from different dimers. By means of charge transfer through the surface, this gives rise to dangling bonds adjacent to the CH(3) groups and chlorine atoms (in effect, 'free radicals') that dissociate further incoming CH(3)Cl molecules, thereby providing the growing points for chains of indefinite length. This versatile mechanism of chain growth is examined in experiments and using ab initio theory.
authors.affiliation: Lash Miller Chemical Laboratories, Department of Chemistry and Institute of Optical Science, University of Toronto, 80 St. George Street, Ontario M5S 3H6, Canada.
authors.forename: Tingbin
authors.initials: T
authors.lastname: Lim
authors.forename: John C
authors.initials: JC
authors.lastname: Polanyi
authors.forename: Hong
authors.initials: H
authors.lastname: Guo
authors.forename: Wei
authors.initials: W
authors.lastname: Ji
mesh_terms: D019281:Dimerization; D054879:Halogenation; D008958:Models, Molecular; D054802:Molecular Imprinting; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D012825:Silicon