title: Electronic control over attachment and self-assembly of alkyne groups on gold.
abstract: Self-assembled monolayers are the basis for molecular nanodevices, flexible surface functionalization, and dip-pen nanolithography. Yet self-assembled monolayers are typically created by a rather inefficient process involving thermally driven attachment reactions of precursor molecules to a metal surface, followed by a slow and defect-prone molecular reorganization. Here we demonstrate a nonthermal, electron-induced approach to the self-assembly of phenylacetylene molecules on gold that allows for a previously unachievable attachment of the molecules to the surface through the alkyne group. While thermal excitation can only desorb the parent molecule due to prohibitively high activation barriers for attachment reactions, localized injection of hot electrons or holes not only overcomes this barrier but also enables an unprecedented control over the size and shape of the self-assembly, defect structures, and the reverse process of molecular disassembly from a single molecule to a mesoscopic length scale. Electron-induced excitation may therefore enable new and highly controlled approaches to molecular self-assembly on a surface.
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Chengbo
authors.initials: C
authors.lastname: Han
authors.forename: Miguel
authors.initials: M
authors.lastname: Fuentes-Cabrera
authors.forename: Humberto
authors.initials: H
authors.lastname: Terrones
authors.forename: Bobby G
authors.initials: BG
authors.lastname: Sumpter
authors.forename: Wenchang
authors.initials: W
authors.lastname: Lu
authors.forename: Jerry
authors.initials: J
authors.lastname: Bernholc
authors.forename: Jieyu
authors.initials: J
authors.lastname: Yi
authors.forename: Zheng
authors.initials: Z
authors.lastname: Gai
authors.forename: Arthur P
authors.initials: AP
authors.lastname: Baddorf
authors.forename: Petro
authors.initials: P
authors.lastname: Maksymovych
authors.forename: Minghu
authors.initials: M
authors.lastname: Pan
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D004595:Electroplating / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D000480:Alkynes; D046911:Macromolecular Substances; D006046:Gold