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Open AccessArticle

Seed-Mediated Synthesis of Thin Gold Nanoplates with Tunable Edge Lengths and Optical Properties

by Zhun Qiao, Xinyu Wei, Hongpo Liu, Kai Liu and Chuanbo Gao

Nanomaterials 2023, 13(4), 711; https://doi.org/10.3390/nano13040711 - 13 Feb 2023

Cited by 7 | Viewed by 4642

Thin Au nanoplates show intriguing localized surface plasmon resonance (LSPR) properties with potential applications in various fields. The conventional synthesis of Au nanoplates usually involves the formation of spherical nanoparticles or produces nanoplates with large thicknesses. Herein, we demonstrate a synthesis of uniform thin Au nanoplates by using Au–Ag alloy nanoframes obtained by the galvanic replacement of Ag nanoplates with HAuCl₄ as the seeds and a sulfite (SO₃²⁻) as a ligand. The SO₃²⁻ ligand not only complexes with the Au salt for the controlled reduction kinetics but also strongly adsorbs on Au {111} facets for effectively constraining the crystal growth on both basal sides of the Au nanoplates for controlled shape and reduced thicknesses. This seed-mediated synthesis affords Au nanoplates with a thickness of only 7.5 nm, although the thickness increases with the edge length. The edge length can be customizable in a range of 48–167 nm, leading to tunable LSPR bands in the range of 600–1000 nm. These thin Au nanoplates are applicable not only to surface-enhanced Raman spectroscopy with enhanced sensitivity and reliability but also to a broader range of LSPR-based applications. Full article

(This article belongs to the Special Issue The Properties of Functional Nanomaterials and Their Energy and Environmental Applications)

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13 pages, 2639 KB

Open AccessArticle

The Design and Optimization of Plasmonic Crystals for Surface Enhanced Raman Spectroscopy Using the Finite Difference Time Domain Method

by Alec Bigness and Jason Montgomery

Materials 2018, 11(5), 672; https://doi.org/10.3390/ma11050672 - 26 Apr 2018

Cited by 5 | Viewed by 4461

Abstract

We present computational studies of quasi three-dimensional nanowell (NW) and nanopost (NP) plasmonic crystals for applications in surface enhanced Raman spectroscopy (SERS). The NW and NP plasmonic crystals are metal coated arrays of cylindrical voids or posts, respectively, in a dielectric substrate characterized [...] Read more.

R D

), periodicity (P), and metal thickness (

M T

). Each plasmonic crystal is modeled using the three-dimensional finite-difference time-domain (FDTD) method with periodic boundary conditions in the x- and y-directions applied to a computational unit cell to simulate the effect of a periodic array. Relative SERS responses are calculated from time-averaged electric field intensity enhancements at

λ_{exc}

and

λ_{scat}

or at

λ_{mid}

via

G_{SERS}^{4} = g^{2} (λ_{exc}) \times g^{2} (λ_{scat})

G_{mid}^{4} = g^{4} (λ_{mid})

, respectively, where

g^{2} = {| E |}^{2} / {| E_{0} |}^{2}

. Comparisons of

G_{SERS}^{4}

and

G_{mid}^{4}

are made to previously reported experimental SERS measurements for NW and NP geometries. Optimized NW and NP configurations based on variations of D, P,

R D

, and

M T

using

G_{SERS}^{4}

are presented, with 6× and 2× predicted increases in SERS, respectively. A novel plasmonic crystal based on square NP geometries are considered with an additional 3× increase over the optimized cylindrical NP geometry. NW geometries with imbedded spherical gold nanoparticles are considered, with 10× to 10

^{3} \times

increases in SERS responses over the NW geometry alone. The results promote the use of FDTD as a viable in silico route to the design and optimization of SERS active devices. Full article

(This article belongs to the Special Issue SERS-Active Substrates)

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