title: Surface-enhanced Raman spectroscopy to probe photoreaction pathways and kinetics of isolated reactants on surfaces: flat versus curved substrates.
abstract: We identify and control the photoreaction paths of self-assembled monolayers (SAMs) of thiolate-linked anthracene phenylethynyl molecules on Au substrate surfaces, and study the effects of nanoscale morphology of substrates on regioselective photoreactions. Two types of morphologies, atomically flat and curved, are produced on Au surfaces by controlling substrate structure and metal deposition. We employ surface-enhanced Raman spectroscopy (SERS), combined with Raman mode analyses using density functional theory, to identify the different photoreaction paths and to track the photoreaction kinetics and efficiencies of molecules in monolayers. The SAMs on curved surfaces exhibit dramatically lower regioselective photoreaction kinetics and efficiencies than those on atomically flat surfaces. This result is attributed to the increased intermolecular distances and variable orientations on the curved surfaces. Better understanding of the morphological effects of substrates will enable control of nanoparticle functionalization in ligand exchange in targeted delivery of therapeutics and theranostics and in catalysis.
authors.affiliation: California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Yue Bing
authors.initials: YB
authors.lastname: Zheng
authors.forename: John L
authors.initials: JL
authors.lastname: Payton
authors.forename: Tze-Bin
authors.initials: TB
authors.lastname: Song
authors.forename: Bala Krishna
authors.initials: BK
authors.lastname: Pathem
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Zhao
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Lasse
authors.initials: L
authors.lastname: Jensen
authors.forename: Alex K-Y
authors.initials: AK
authors.lastname: Jen
authors.forename: Paul S
authors.initials: PS
authors.lastname: Weiss