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Issue 9, 2011
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Plasmon-induced modulation of the emission spectra of the fluorescent molecules near gold nanorods

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Abstract

Both the excitation and emission processes of a fluorescent molecule positioned near a noble metal nanocrystal can interact strongly with the localized surface plasmon resonance of the metal nanocrystal. While the effects of this plasmon–fluorophore interaction on the intensity, polarization, and direction of the fluorescence emission have been intensively investigated, the plasmonic effect on the emission spectrum has barely been explored. We show, on the single-particle level, that the localized surface plasmon resonance of Au nanorods can strongly alter the spectral profile of the emission from adjacent fluorescent molecules. The fluorescent molecules are embedded in a mesostructured silica shell that is uniformly coated on each Au nanorod. The longitudinal plasmon resonance wavelengths of the nanorods are deliberately shifted away from the intrinsic fluorescence emission peak wavelength by synthetically tuning the nanorod aspect ratio. The resultant emission spectra of the fluorescent molecules are found to be remarkably modulated. Besides the intrinsic fluorescence peak, a plasmon-induced new peak emerges at the plasmon resonance wavelength. The intensity of this plasmon-induced fluorescence peak increases as the size of the Au nanorod is increased. This spectral modulation can be understood by depicting the decay process of the fluorophore with multiple vibrational energy levels. The plasmon with a specific resonance energy will enhance the transition rate between the energy levels that have the transition energy approximately equal to the plasmon energy. This plasmon-enhanced transition rate results in a modulated spectral profile of the fluorescence emission.

Graphical abstract: Plasmon-induced modulation of the emission spectra of the fluorescent molecules near gold nanorods

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Publication details

The article was received on 28 May 2011, accepted on 08 Jul 2011 and first published on 08 Aug 2011


Article type: Paper
DOI: 10.1039/C1NR10544B
Citation: Nanoscale, 2011,3, 3849-3859
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    Plasmon-induced modulation of the emission spectra of the fluorescent molecules near gold nanorods

    L. Zhao, T. Ming, H. Chen, Y. Liang and J. Wang, Nanoscale, 2011, 3, 3849
    DOI: 10.1039/C1NR10544B

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