Plasmonic Interactions at Close Proximity in Chiral Geometries: Route toward Broadband Chiroptical Response and Giant Enantiomeric Sensitivity

Nair, Greshma and Singh, Haobijam Johnson and Paria, Debadrita and Venkatapathi, Murugesan and Ghosh, Ambarish (2014) Plasmonic Interactions at Close Proximity in Chiral Geometries: Route toward Broadband Chiroptical Response and Giant Enantiomeric Sensitivity. In: JOURNAL OF PHYSICAL CHEMISTRY C, 118 (9). pp. 4991-4997.

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Abstract

Chiral metamaterials can have diverse technological applications, such as engineering strongly twisted local electromagnetic fields for sensitive detection of chiral molecules, negative indices of refraction, broadband circular polarization devices, and many more. These are commonly achieved by arranging a group of noble-metal nanoparticles in a chiral geometry, which, for example, can be a helix, whose chiroptical response originates in the dynamic electromagnetic interactions between the localized plasmon modes of the individual nanoparticles. A key question relevant to the chiroptical response of such materials is the role of plasmon interactions as the constituent particles are brought closer, which is investigated in this paper through theoretical and experimental studies. The results of our theoretical analysis, when the particles are brought in close proximity are dramatic, showing a large red shift and enhancement of the spectral width and a near-exponential rise in the strength of the chiroptical response. These predictions were further confirmed with experimental studies of gold and silver nanoparticles arranged on a helical template, where the role of particle separation could be investigated in a systematic manner. The ``optical chirality'' of the electromagnetic fields in the vicinity of the nanoparticles was estimated to be orders of magnitude larger than what could be achieved in all other nanoplasmonic geometries considered so far, implying the suitability of the experimental system for sensitive detection of chiral molecules.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY C
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copyright for this article belongs to the AMER CHEMICAL SOC, USA
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering Division of Physical & Mathematical Sciences > Physics
Date Deposited:	19 May 2014 08:29
Last Modified:	19 May 2014 08:29
URI:	http://eprints.iisc.ac.in/id/eprint/48949

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