title: Antibonding plasmon modes in colloidal gold nanorod clusters.
abstract: The optical response of nanoplasmonic colloids in disperse phase is strictly related to their shape. However, upon self-assembly, new optical features, for example, bonding or antibonding modes, emerge as a result of the mutual orientations of nanoparticles. The geometry of the final assemblies often determines which mode is dominating in the overall optical response. These new plasmon modes, however, are mostly observed in silico, as self-assembly in the liquid phase leads to cluster formation with a broad range of particle units. Here we show that low-symmetry clustering of gold nanorods (AuNRs) in solution can also reveal antibonding modes. We found that UV-light irradiation of colloidal dispersions of AuNRs in N-methyl-2-pyrrolidone (NMP), stabilized by poly(vinylpyrrolidone) (PVP) results in the creation of AuNRs clusters with ladderlike morphology, where antibonding modes can be identified. We propose that UV irradiation induces formation of radicals in solvent molecules, which then promote cross-linking of PVP chains on the surface of adjacent particles. This picture opens up a number of relevant questions in nanoscience and is expected to find application in light induced self-assembly of particles with various compositions and morphologies.
authors: Department of Chemical and Pharmaceutical Sciences, University of Trieste, P.le Europa 1, 34127 Trieste Italy. grzelczak.marek@gmail.com
authors: Marek
authors: M
authors: Grzelczak
authors: Stefano A
authors: SA
authors: Mezzasalma
authors: Weihai
authors: W
authors: Ni
authors: Yury
authors: Y
authors: Herasimenka
authors: Luigi
authors: L
authors: Feruglio
authors: Tiziano
authors: T
authors: Montini
authors: Jorge
authors: J
authors: Pérez-Juste
authors: Paolo
authors: P
authors: Fornasiero
authors: Maurizio
authors: M
authors: Prato
authors: Luis M
authors: LM
authors: Liz-Marzán
mesh_terms: D003102:Colloids / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D010316:Particle Size; D011205:Povidone / Q000737:chemistry; D011760:Pyrrolidinones / Q000737:chemistry; D013499:Surface Properties; D014466:Ultraviolet Rays
chemical_list: D003102:Colloids; D011760:Pyrrolidinones; D006046:Gold; D011205:Povidone; C038678:N-methylpyrrolidone