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The role of a plasmonic substrate on the enhancement and spatial resolution of tip-enhanced Raman scattering. / Rahaman, Mahfujur; Milekhin, Alexander G.; Mukherjee, Ashutosh и др.
в: Faraday Discussions, Том 214, 01.05.2019, стр. 309-323.Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
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TY - JOUR
T1 - The role of a plasmonic substrate on the enhancement and spatial resolution of tip-enhanced Raman scattering
AU - Rahaman, Mahfujur
AU - Milekhin, Alexander G.
AU - Mukherjee, Ashutosh
AU - Rodyakina, Ekaterina E.
AU - Latyshev, Alexander V.
AU - Dzhagan, Volodymyr M.
AU - Zahn, Dietrich R.T.
PY - 2019/5/1
Y1 - 2019/5/1
N2 - Since the first report in the early 2000s, there have been several experimental configurations that have demonstrated enhancement and spatial resolution of tip-enhanced Raman spectroscopy (TERS). The combination of a plasmonic substrate and a metallic tip is one suitable approach to achieve even higher enhancement and lateral resolution. In this contribution, we demonstrate TERS on a monolayer of MoS2 on an array of Au nanodisks. The Au nanodisks were prepared by electron beam writing. Thereafter, MoS2 was transferred onto the plasmonic substrate via the exfoliation technique. We witness an unprecedented enhancement and spatial resolution in the experiments. In the TERS image a ring-like shape is observed that matches the edges of the nanodisks. TERS enhancement at the edges is about 170 times stronger than at the center of the nanodisks. For a better understanding of the experimental results, finite element method (FEM) simulations were employed to simulate the TERS image of the MoS2/plasmonic heterostructure. Our calculations show a higher electric field concentration at the edges that exponentially decays to the center. Therefore, it reproduces the ring-like shape of the experimental image. Moreover, the calculations suggest a TERS enhancement of 135 at the edges compared to the center, which is in very good agreement with the experimental data. According to our calculations, the spatial resolution is also increased at the edges. For comparison, FEM simulations of a tip-flat metal substrate system (conventional gap-mode TERS) were carried out. The calculations confirmed a 110 times stronger enhancement at the edges of the nanodisks than that of conventional gap-mode TERS and explained the experimental maps. Our results provide not only a deeper understanding of the TERS mechanism of this heterostructure, but can also help in realizing highly efficient TERS experiments using similar systems.
AB - Since the first report in the early 2000s, there have been several experimental configurations that have demonstrated enhancement and spatial resolution of tip-enhanced Raman spectroscopy (TERS). The combination of a plasmonic substrate and a metallic tip is one suitable approach to achieve even higher enhancement and lateral resolution. In this contribution, we demonstrate TERS on a monolayer of MoS2 on an array of Au nanodisks. The Au nanodisks were prepared by electron beam writing. Thereafter, MoS2 was transferred onto the plasmonic substrate via the exfoliation technique. We witness an unprecedented enhancement and spatial resolution in the experiments. In the TERS image a ring-like shape is observed that matches the edges of the nanodisks. TERS enhancement at the edges is about 170 times stronger than at the center of the nanodisks. For a better understanding of the experimental results, finite element method (FEM) simulations were employed to simulate the TERS image of the MoS2/plasmonic heterostructure. Our calculations show a higher electric field concentration at the edges that exponentially decays to the center. Therefore, it reproduces the ring-like shape of the experimental image. Moreover, the calculations suggest a TERS enhancement of 135 at the edges compared to the center, which is in very good agreement with the experimental data. According to our calculations, the spatial resolution is also increased at the edges. For comparison, FEM simulations of a tip-flat metal substrate system (conventional gap-mode TERS) were carried out. The calculations confirmed a 110 times stronger enhancement at the edges of the nanodisks than that of conventional gap-mode TERS and explained the experimental maps. Our results provide not only a deeper understanding of the TERS mechanism of this heterostructure, but can also help in realizing highly efficient TERS experiments using similar systems.
KW - SINGLE-MOLECULE
KW - OPTICAL-PROPERTIES
KW - CHEMICAL-ANALYSIS
KW - LOCALIZED STRAIN
KW - HOT-SPOTS
KW - SPECTROSCOPY
KW - SURFACE
KW - NANOSCALE
KW - MICROSCOPY
KW - CONTRAST
UR - http://www.scopus.com/inward/record.url?scp=85066496227&partnerID=8YFLogxK
U2 - 10.1039/c8fd00142a
DO - 10.1039/c8fd00142a
M3 - Article
C2 - 30839033
AN - SCOPUS:85066496227
VL - 214
SP - 309
EP - 323
JO - Faraday Discussions
JF - Faraday Discussions
SN - 1364-5498
ER -
ID: 20344996