Near-Field Optical Properties of Ag x Au1−x Nanoparticle Chains Embedded in a Dielectric Matrix
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- 作者：Alexandre Fafin ; Senda Yazidi ; Sophie Camelio ; David Babonneau
- 关键词：Localized surface plasmon resonance (LSPR) ; Ag ; Au alloy nanoparticles ; Finite ; difference time ; domain method (FDTD) ; Near ; field enhancement ; Hot spots
- 刊名：Plasmonics
- 出版年：2016
- 出版时间：October 2016
- 年：2016
- 卷：11
- 期：5
- 页码：1407-1416
- 全文大小：1,641 KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry
Biotechnology
Nanotechnology
Biophysics and Biomedical Physics
Biochemistry - 出版者：Springer US
- ISSN：1557-1963
- 卷排序：11
文摘
We study by the finite-difference time-domain method the near-field optical properties of isolated or coupled AgxAu1−x alloy nanoparticles shallowly buried inside dielectric matrices. The optical index of alloys is obtained experimentally using spectroscopic ellipsometry measurements from multilayered thin films fabricated by ion-beam sputtering. Then, we numerically investigate the influence of the nanoparticle composition, interparticle gap and capping-layer thickness on the amplitude and spatial extent of the electric field in the vicinity of ellipsoidal nanoparticles. Our calculations provide evidence that pure metal nanoparticles (Ag or Au) exhibit a greater field enhancement associated with a larger out-of-plane extent compared to alloy nanoparticles, an effect that is even more pronounced when the optical index of surrounding matrix is increased. Moreover, we show that the optimal gap between nanoparticles to maximize the amplitude of the electric field at the capping layer/air interface results from a delicate balance, which strongly depends on the thickness of the dielectric capping layer.