title: Surface-enhanced spectroscopy on plasmonic oligomers assembled by AFM nanoxerography.
abstract: Surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) from individual plasmonic oligomers are investigated by confocal Raman micro-spectroscopy and time-resolved fluorescence microscopy coupled to steady state micro-spectroscopy. The nanoparticle (NP) oligomers are made of either ligand protected Au or Au@SiO2 core-shell colloidal NPs, which were assembled into ordered arrays by atomic force microscopy (AFM) nanoxerography. A strong dependence of the SERS emission on the polarization of incident light relative to the specific geometry of the plasmonic oligomer was observed. The SEF studies, performed on a large collection of NP oligomers of various known configurations showed interesting fluorophore decay rate modification and red-shift of the emission spectra. The experimental results are analyzed theoretically by employing finite-difference time-domain (FDTD) simulations on equivalent realistic structures, within the local density of optical states (LDOS) framework. The presented results, together with the proven potential of the LDOS approach as a useful common tool for analyzing both SERS and SEF effects further the general understanding of plasmon-related phenomena in nanoparticle oligomers.
authors.affiliation: Université de Toulouse, LPCNO, INSA-CNRS-UPS, 135 Avenue de Rangueil, Toulouse, 31077, France. laurence.ressier@insa-toulouse.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Moutet
authors.forename: Neralagatta M
authors.initials: NM
authors.lastname: Sangeetha
authors.forename: Laurence
authors.initials: L
authors.lastname: Ressier
authors.forename: Noelia
authors.initials: N
authors.lastname: Vilar-Vidal
authors.forename: Miguel
authors.initials: M
authors.lastname: Comesaña-Hermo
authors.forename: Serge
authors.initials: S
authors.lastname: Ravaine
authors.forename: Renaud A L
authors.initials: RA
authors.lastname: Vallée
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Gabudean
authors.forename: Simion
authors.initials: S
authors.lastname: Astilean
authors.forename: Cosmin
authors.initials: C
authors.lastname: Farcau