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Quantitatively analyzing the mechanism of giant circular dichroism in extrinsic plasmonic chiral nanostructures by tracking the interplay of electric and magnetic dipoles

H. A. Li ; X. R. Tian ; Y. Z. Huang ; L. Fang ; Yurui Fang (Institutionen för fysik, Bionanofotonik (Chalmers))
Nanoscale (2040-3364). Vol. 8 (2016), 6, p. 3720-3728.
[Artikel, refereegranskad vetenskaplig]

Plasmonic chirality has drawn much attention because of tunable circular dichroism (CD) and the enhancement for chiral molecule signals. Although various mechanisms have been proposed to explain the plasmonic CD, a quantitative explanation like the ab initio mechanism for chiral molecules, is still unavailable. In this study, a mechanism similar to the mechanisms associated with chiral molecules was analyzed. The giant extrinsic circular dichroism of a plasmonic splitting rectangle ring was quantitatively investigated from a theoretical standpoint. The interplay of the electric and magnetic modes of the meta-structure is proposed to explain the giant CD. We analyzed the interplay using both an analytical coupled electric-magnetic dipole model and a finite element method model. The surface charge distributions showed that the circular current yielded by the splitting rectangle ring causes the ring to behave like a magneton at some resonant modes, which then interact with the electric modes, resulting in a mixing of the two types of modes. The strong interplay of the two mode types is primarily responsible for the giant CD. The analysis of the chiral near-field of the structure shows potential applications for chiral molecule sensing.

Nyckelord: resonances, nanoparticles, nanocrystals, model, Chemistry, Science & Technology - Other Topics, Materials Science, Physics



Denna post skapades 2016-03-09.
CPL Pubid: 232965

 

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Institutioner (Chalmers)

Institutionen för fysik, Bionanofotonik (Chalmers)

Ämnesområden

Fysik

Chalmers infrastruktur