title: Bond insertion, complexation, and penetration pathways of vapor-deposited aluminum atoms with HO- and CH(3)O-terminated organic monolayers.
abstract: The interaction of vapor-deposited Al atoms with self-assembled monolayers (SAMs) of HS-(CH(2))(16)-X (X = -OH and -OCH(3)) chemisorbed at polycrystalline Au[111] surfaces was studied using time-of-flight secondary-ion mass spectrometry, X-ray photoelectron spectroscopy, and infrared reflectance spectroscopy. Whereas quantum chemical theory calculations show that Al insertion into the C-C, C-H, C-O, and O-H bonds is favorable energetically, it is observed that deposited Al inserts only with the OH SAM to form an -O-Al-H product. This reaction appears to cease prior to complete -OH consumption, and is followed by formation of a few overlayers of a nonmetallic type of phase and finally deposition of a metallic film. In contrast, for the OCH(3) SAM, the deposited Al atoms partition along two parallel paths: nucleation and growth of an overlayer metal film, and penetration through the OCH(3) SAM to the monolayer/Au interface region. By considering a previous observation that a CH(3) terminal group favors penetration as the dominant initial process, and using theory calculations of Al-molecule interaction energies, we suggest that the competition between the penetration and overlayer film nucleation channels is regulated by small differences in the Al-SAM terminal group interaction energies. These results demonstrate the highly subtle effects of surface structure and composition on the nucleation and growth of metal films on organic surfaces and point to a new perspective on organometallic and metal-solvent interactions.
authors: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors: Gregory L
authors: GL
authors: Fisher
authors: Amy V
authors: AV
authors: Walker
authors: Andrew E
authors: AE
authors: Hooper
authors: Timothy B
authors: TB
authors: Tighe
authors: Kevin B
authors: KB
authors: Bahnck
authors: Hope T
authors: HT
authors: Skriba
authors: Michael D
authors: MD
authors: Reinard
authors: Brendan C
authors: BC
authors: Haynie
authors: Robert L
authors: RL
authors: Opila
authors: Nicholas
authors: N
authors: Winograd
authors: David L
authors: DL
authors: Allara
mesh_terms: D000438:Alcohols / Q000737:chemistry*; D000535:Aluminum / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry*; D005740:Gases; D006838:Hydrocarbons / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods; D013055:Spectrophotometry, Infrared; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000438:Alcohols; D004987:Ethers; D005740:Gases; D006838:Hydrocarbons; D013438:Sulfhydryl Compounds; D000535:Aluminum