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Magnetic circular dichroism of thiolate-protected plasmonic gold nanoparticles: separating the effects of interband transitions and surface magnetoplasmon resonance

Magnetic circular dichroism of thiolate-protected plasmonic gold nanoparticles: separating the... Abstract. Magneto-optical activity is demonstrated in thiolate-protected Au nanoparticles with magnetic circular dichroism (MCD) spectroscopy. The samples examined are decanethiolate-protected Au nanoparticles with the mean diameters ranging from 2.0 to 4.7 nm. The nanoparticles larger than 2.4 nm in diameter exhibit a derivative-like MCD signal, indicating the presence of two circular modes of surface magnetoplasmon, but the spectral shape is so asymmetric that its identification is rather difficult. This is due to the contribution of interband transitions occurring at around the localized surface plasmon resonance (LSPR) frequency. We then develop an efficient method to phenomenologically separate the effects of magnetoplasmonic intraband (= Drude) and interband transitions in the measured MCD spectra using an approximation that the optical response of the Au nanoparticle with a critical size ( ∼ 2.0 nm ) for the disappearance of LSPR, which is also experimentally obtainable, is substantially dominated by the interband transitions. The consistency of the method is ensured for tiopronin-protected Au nanoparticles, and a very small bisignate magnetoplasmonic response hidden in the total MCD spectrum can be extracted. The practical advantage of the proposed method is that we can intuitively and effectively evaluate the characteristic features of the surface magnetoplasmon of thiolate-protected Au nanoparticles without performing complicated Mie or quasielectrostatic calculations. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Nanophotonics SPIE

Magnetic circular dichroism of thiolate-protected plasmonic gold nanoparticles: separating the effects of interband transitions and surface magnetoplasmon resonance

Shiratsu, Taisuke; Yao, Hiroshi
Journal of Nanophotonics , Volume 10 (4) – Oct 1, 2016
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References (23)

Publisher
SPIE
Copyright
© 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)
Subject
Research Papers; Paper
ISSN
1934-2608
eISSN
1934-2608
DOI
10.1117/1.JNP.10.046004
Publisher site
See Article on Publisher Site

Abstract

Abstract. Magneto-optical activity is demonstrated in thiolate-protected Au nanoparticles with magnetic circular dichroism (MCD) spectroscopy. The samples examined are decanethiolate-protected Au nanoparticles with the mean diameters ranging from 2.0 to 4.7 nm. The nanoparticles larger than 2.4 nm in diameter exhibit a derivative-like MCD signal, indicating the presence of two circular modes of surface magnetoplasmon, but the spectral shape is so asymmetric that its identification is rather difficult. This is due to the contribution of interband transitions occurring at around the localized surface plasmon resonance (LSPR) frequency. We then develop an efficient method to phenomenologically separate the effects of magnetoplasmonic intraband (= Drude) and interband transitions in the measured MCD spectra using an approximation that the optical response of the Au nanoparticle with a critical size ( ∼ 2.0 nm ) for the disappearance of LSPR, which is also experimentally obtainable, is substantially dominated by the interband transitions. The consistency of the method is ensured for tiopronin-protected Au nanoparticles, and a very small bisignate magnetoplasmonic response hidden in the total MCD spectrum can be extracted. The practical advantage of the proposed method is that we can intuitively and effectively evaluate the characteristic features of the surface magnetoplasmon of thiolate-protected Au nanoparticles without performing complicated Mie or quasielectrostatic calculations.

Journal

Journal of Nanophotonics – SPIE

Published: Oct 1, 2016

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