周期性银纳米皿作为敏感且可重现的表面增强拉曼散射底物
111 浏览量
2021-02-25
21:01:45
上传
评论
收藏 256KB PDF 举报
Periodic silver nanodishes as sensitive and
reproducible surface-enhanced Raman scattering
substrates†
Wenyu Tao,
abc
Aiwu Zhao,
*
ac
Henghui Sun,
a
Zibao Gan,
a
Maofeng Zhang,
a
Da Li
a
and Hongyan Guo
a
Highly ordered silver nanodishes which consist of nanorings and a film were fabricated as surface-
enhanced Raman scattering (SERS) substrates. Numerical simulation reveals the bottom film can
dramatically enhance the local electromagnetic (EM) field in the ring cavity, due to the plasmonic
interaction between the nanorings and the film. Raman results show that the nanodishes can produce
about sevenfold stronger signal than the nanorings alone, in accordance with the theoretical simulation.
The detection limit for Rhodamine 6G (R6G) in the order of 10
12
M and the average relative standard
deviation (RSD) of less than 12% indicate the excellent sensitivity and reproducibility of silver nanodishes.
The SERS enhancement factor (EF) of R6G on the nanodishes was calculated to be 6.17 10
7
. For
practical application, the silver nanodishes were also used to detect thiram, one dithiocarbamate
fungicide that has been extensively used as a pesticide in agriculture. The detection limit of thiram
molecules is as low as 1 10
7
M, which can meet the requirements for ultra trace detection of
pesticide residues. The resulting substrate with high SERS activity, stability and reproducibility makes it a
perfect choice for practical SERS detection applications.
1. Introduction
Surface-enhanced Raman scattering (SERS) is a powerful
analytical tool which can greatly enhance the Raman signal of
analytes and makes the ultra trace detection of chemical and
biological molecules possible.
1,2
Electromagnetic (EM) mecha-
nism and chemical mechanism are widely accepted as two main
mechanisms accounting for such an enormous Raman
enhancement.
3–5
The EM mechanism is closely related to the
surface plasmon resonance (SPR), which leads to a giant
amplication of the local electromagnetic eld. It has been
reported that the small gaps between two nanoparticles (NPs) or
sharp edges of nanostructures, usually called “hot spots”, are
essential to exciting SPR.
6
Normally, the EM mechanism is
considered as the predominant mechanism.
Since the discovery of SERS
7
in 1974, a large variety of SERS
substrates with high EM enhancement have been extensively
explored.
8,9
NPs synthesized in solution with controllable
shapes and sizes usually have high enhancement because of the
large number of hot spots formed in their aggregations.
10–13
However, it is very difficult to control the homogeneity of the
aggregations of NPs in these systems. Consequently, the hot
spots are randomly distributed and will lead to a poor repro-
ducibility. As we know, to realize the practical application of
SERS technology, some important factors such as the repro-
ducibility, uniformity and stability also have to be taken into
account except for the large Raman enhancement. Periodic
nanostructures comprised of ordered metallic NPs exhibit
special advantages in reproducibility, as a result of the uniform
morphology. Many periodic nanostructures such as nanor-
ings,
14–16
nanobowls,
17
nanopyramids
18
and nanocrescents
19
have been explored. In particular, nanorings are of great
interest due to their tunable localized surface plasmon and the
nanocavities which can hold other small nanostructures.
20
E-beam lithography has been extensively applied to fabricate
periodic nanorings but the low throughput and high cost have
limited its further use. Alternatively, nanosphere lithography
(NSL) technique is a facile and cost-effective method for fabri-
cating ordered nanostructures on a large scale.
21
Herein, we prepared highly ordered silver nanorings and
nanodishes by NSL technique and explored their applications in
SERS, considering that the silver nanomaterials have the best
SERS properties. Ye and coworkers have fabricated gold
nanorings–SiO
2
–gold lm structure and found the SERS
performances can get optimized by tuning the thicknesses of
a
Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, China.
E-mail: awzhao@iim.ac.cn
b
Department of Chemistry, University of Science and Technology of China, Hefei
230026, China
c
State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Hefei
230031, China
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c3ra45935g
Cite this: RSC Adv.,2014,4, 3487
Received 19th October 2013
Accepted 25th November 2013
DOI: 10.1039/c3ra45935g
www.rsc.org/advances
This journal is © The Royal Society of Chemistry 2014 RSC Adv.,2014,4,3487–3493 | 3487
RSC Advances
PAPER
Published on 27 November 2013. Downloaded by McGill University on 11/09/2014 02:49:40.
View Article Online
View Journal
| View Issue
评论0