title: Photoluminescence of a Plasmonic Molecule.
abstract: Photoluminescent Au nanoparticles are appealing for biosensing and bioimaging applications because of their non-photobleaching and non-photoblinking emission. The mechanism of one-photon photoluminescence from plasmonic nanostructures is still heavily debated though. Here, we report on the one-photon photoluminescence of strongly coupled 50 nm Au nanosphere dimers, the simplest plasmonic molecule. We observe emission from coupled plasmonic modes as revealed by single-particle photoluminescence spectra in comparison to correlated dark-field scattering spectroscopy. The photoluminescence quantum yield of the dimers is found to be surprisingly similar to the constituent monomers, suggesting that the increased local electric field of the dimer plays a minor role, in contradiction to several proposed mechanisms. Aided by electromagnetic simulations of scattering and absorption spectra, we conclude that our data are instead consistent with a multistep mechanism that involves the emission due to radiative decay of surface plasmons generated from excited electron-hole pairs following interband absorption.
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Da
authors.initials: D
authors.lastname: Huang
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Chad P
authors.initials: CP
authors.lastname: Byers
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Lin-Yung
authors.initials: LY
authors.lastname: Wang
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Anneli
authors.initials: A
authors.lastname: Hoggard
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Ben
authors.initials: B
authors.lastname: Hoener
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Sergio
authors.initials: S
authors.lastname: Dominguez-Medina
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Sishan
authors.initials: S
authors.lastname: Chen
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Wei-Shun
authors.initials: WS
authors.lastname: Chang
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Christy F
authors.initials: CF
authors.lastname: Landes
authors.affiliation: †Department of Chemistry and ‡Department of Electrical and Computer Engineering Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States.
authors.forename: Stephan
authors.initials: S
authors.lastname: Link
keywords: gold nanoparticle; nanoparticle dimer; photoluminescence; plasmon coupling; surface plasmon