title: Versatile Gap Mode Plasmon under ATR Geometry towards Single Molecule Raman, Laser Trapping and Photocatalytic Reactions.
abstract: We have investigated various aspects of a gap mode plasmon to establish it as an analytical tool. First, markedly large (107- 109) enhancement factors for the Raman scattering intensity from a thiophenol (TP) monolayer sandwiched by Ag films on a prism and silver nanoparticles (AgNPs) were obtained under attenuated total reflection (ATR) geometry. Second, AgNPs with a radius of ∼20 nm were optically trapped and immobilized on TP-covered Ag films under a gap mode resonance with extremely weak laser power density of ∼1 μW/μm2at 532 nm. The observed optical trapping and immobilization were theoretically rationalized using a dipole-dipole coupling and van der Waals interaction between AgNPs and Ag films. Third, p-alkyl TP molecules such as p-methyl TP, p-ethyl TP, p-isopropyl TP, and p-tertiary butyl TP were photocatalytically oxidized into p-carboxyl TP, whereas o- and m-methyl TP did not show such reactions.
authors.affiliation: Graduate School of Science and Engineering, Saitama University.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Futamata
authors.forename: Keitaro
authors.initials: K
authors.lastname: Akai
authors.forename: Chiaki
authors.initials: C
authors.lastname: Iida
authors.forename: Natsumi
authors.initials: N
authors.lastname: Akiba