Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Plasmonic Properties of Bimetallic Quantum Dot Ag@Au Core-Shell Nanostructures Embedded in Non-Absorptive Host Medium

Version 1 : Received: 15 April 2021 / Approved: 16 April 2021 / Online: 16 April 2021 (10:45:14 CEST)

How to cite: Kassahun, G.B.B. Plasmonic Properties of Bimetallic Quantum Dot Ag@Au Core-Shell Nanostructures Embedded in Non-Absorptive Host Medium. Preprints 2021, 2021040435 (doi: 10.20944/preprints202104.0435.v1). Kassahun, G.B.B. Plasmonic Properties of Bimetallic Quantum Dot Ag@Au Core-Shell Nanostructures Embedded in Non-Absorptive Host Medium. Preprints 2021, 2021040435 (doi: 10.20944/preprints202104.0435.v1).

Abstract

This studies the plasmonic properties of the bimetallic quantum dot Ag@Au core-shell nanostructures embedded in the non-absorbent host medium. Local field enhancement factor and coefficient of absorption of Ag-core and Au-shell are primarily studied based on quasi-static approximation of classical electrodynamics for 6-10 nm composite radius. In this quantum dot geometry, two set of plasmonic resonances in visible spectral region are observed: the first resonance associated with inner interface of gold (Ag@Au) and the second resonance associated with outer interface of gold (Au@medium). The two plasmonic resonances are close each other and enhanced when the size of composite decreased for a fixed core size while shifted to in opposite direction and the amplitude of peak decreased when the core size is increased for a fixed composite size. For the optimized size of core/composite or shell thickness and other parameters to the desired values, such type of composites are recommended for various applications like; photocatalysis, biomedical, nano-optoelectronics.

Keywords

Core-Shell; Spacer; Host-Medium; Bimetallic; Enhancement Factor; Dielectrics Function

Subject

MATERIALS SCIENCE, Surfaces, Coatings & Films

Comments (1)

Comment 1
Received: 31 May 2021
The commenter has declared there is no conflict of interests.
Comment: The interpretation of the results contradicts the common sense, which tells that the plasmon modes of bimetal core-shell particles do not hybridize. A convincing study of this effect can be found in the following paper:
Velichko, E.A. Localized surface plasmon modes of core–shell bimetal nanowires do not hybridize
Journal of the Optical Society of America A, 2020, 37(9), pp. 1411–1416

Thus, there is no plasmon mode associated with the inner surface of the gold shell on the silver core - instead, if the shell is thinner than the skindepth, the resonance on the surface of the silver core becomes visible.

Another comment is that using the Drude formulas for the Au and Ag permittivities in the modeling of the resonances in the scattering from circular and spherical particles is heavily erroneous. This is because their plasmon resonances are in the ultra-violet range, where Drude's one-term formula yields 100% error. The way out is in using multi-term Drude-like formulas or simply using the Jonson and Christy experimental results for the epsilon function.
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