title: Cluster Plasmonics: Dielectric and Shape Effects on DNA-Stabilized Silver Clusters.
abstract: This work investigates the effects of dielectric environment and cluster shape on electronic excitations of fluorescent DNA-stabilized silver clusters, AgN-DNA. We first establish that the longitudinal plasmon wavelengths predicted by classical Mie-Gans (MG) theory agree with previous quantum calculations for excitation wavelengths of linear silver atom chains, even for clusters of just a few atoms. Application of MG theory to AgN-DNA with 400-850 nm cluster excitation wavelengths indicates that these clusters are characterized by a collective excitation process and suggests effective cluster thicknesses of ∼2 silver atoms and aspect ratios of 1.5 to 5. To investigate sensitivity to the surrounding medium, we measure the wavelength shifts produced by addition of glycerol. These are smaller than reported for much larger gold nanoparticles but easily detectable due to narrower line widths, suggesting that AgN-DNA may have potential for fluorescence-reported changes in dielectric environment at length scales of ∼1 nm.
authors.affiliation: Department of Physics, University of California , Santa Barbara, California 93106-9530, United States.
authors.forename: Stacy M
authors.initials: SM
authors.lastname: Copp
authors.affiliation: Department of Chemistry, University of California , Santa Barbara, California 93106-9510, United States.
authors.forename: Danielle
authors.initials: D
authors.lastname: Schultz
authors.affiliation: Department of Chemistry, University of California , Santa Barbara, California 93106-9510, United States.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Swasey
authors.affiliation: Department of Physics, University of California , Santa Barbara, California 93106-9530, United States.
authors.forename: Alexis
authors.initials: A
authors.lastname: Faris
authors.affiliation: Department of Physics, University of California , Santa Barbara, California 93106-9530, United States.
authors.forename: Elisabeth G
authors.initials: EG
authors.lastname: Gwinn
mesh_terms: D003116:Color; D004247:DNA / Q000737:chemistry*; D004553:Electric Conductivity; D005453:Fluorescence; D005990:Glycerol / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011789:Quantum Theory; D012834:Silver / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D012834:Silver; D006046:Gold; D004247:DNA; D005990:Glycerol
keywords: DNA; Metal cluster; Mie−Gans theory; dielectric sensing; fluorescence