Cluster Plasmonics: Dielectric and Shape Effects on DNA-Stabilized Silver Clusters

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• 作者：Stacy M. Copp ; Danielle Schultz ; Steven M. Swasey ; Alexis Faris ; Elisabeth G. Gwinn
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：June 8, 2016
• 年：2016
• 卷：16
• 期：6
• 页码：3594-3599
• 全文大小：348K
• 年卷期：0
• ISSN：1530-6992

文摘

This work investigates the effects of dielectric environment and cluster shape on electronic excitations of fluorescent DNA-stabilized silver clusters, Ag_N–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 Ag_N–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 Ag_N–DNA may have potential for fluorescence-reported changes in dielectric environment at length scales of ∼1 nm.