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Single Particle Study: Size and Chemical Effects on Plasmon Damping at the Interface between Adsorbate and Anisotropic Gold Nanorods

Abstract

Plasmon damping in gold nanorods (AuNRs) results in the broadening of the localized surface plasmon resonance (LSPR) linewidth. LSPR broadening of plasmonic nanoparticles is useful to maximize fraction of light energy in light harvesting and energy conversion transferred to attached molecules on the surface. However, our understanding of plasmon decay channels in AuNRs is still limited, and chemical interface damping (CID) is the most poorly understood damping mechanism. Herein, to better understand plasmon damping including CID, we performed single particle study of plasmonic anisotropic AuNRs under dark-field (DF) microscopy and spectroscopy. First, we examined size-dependent broadening of the homogeneous LSPR linewidth of single AuNRs in water with three different aspect ratios (ARs) at a fixed diameter of 25 nm. The LSPR linewidth increased with decreasing the AR of single AuNRs because of the reduced average distance of hot electrons to the surface. Second, we investigated the effect of refractive index variation of the surrounding medium on the LSPR linewidth in single AuNRs of three different sizes. The LSPR linewidth in single AuNRs remained almost constant regardless of their sizes while increasing the dielectric constant of the medium. Finally, we examined the effect of adsorbate thiol molecules on the homogeneous LSPR linewidth of single AuNRs in ethanol. The LSPR linewidth was broadened with increasing the carbon chain length of 1-alkanethiol, and 4-nitrothiophenol with strong electron withdrawing group induced a large broadening in the LSPR linewidth. Furthermore, signel AuNRs with smaller ARs showed a larger broadening in the LSPR linewidth in the presence of adsorbate thiol molecules through CID. Therefore, this investigation provides a deeper insight into the size effect on plasmon damping including CID induced by chemical interface effect in single AuNRs.

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Supplementary files

Publication details

The article was received on 21 May 2018, accepted on 01 Aug 2018 and first published on 02 Aug 2018


Article type: Paper
DOI: 10.1039/C8CP03231A
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Single Particle Study: Size and Chemical Effects on Plasmon Damping at the Interface between Adsorbate and Anisotropic Gold Nanorods

    S. W. Moon, P. V. Tsalu and J. W. Ha, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP03231A

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