scholarly journals Raman Signal Enhancement Tunable by Gold-Covered Porous Silicon Films with Different Morphology

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5634 ◽  
Author(s):  
Svetlana N. Agafilushkina ◽  
Olga Žukovskaja ◽  
Sergey A. Dyakov ◽  
Karina Weber ◽  
Vladimir Sivakov ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Raman Scattering ◽  
Pore Size ◽  
Signal Enhancement ◽  
Raman Signal ◽  
Sers Spectrum ◽  
Internal Diameter ◽  
Au Nps ◽  
Surface Enhanced Raman ◽  
Size And Morphology

The ease of fabrication, large surface area, tunable pore size and morphology as well surface modification capabilities of a porous silicon (PSi) layer make it widely used for sensoric applications. The pore size of a PSi layer can be an important parameter when used as a matrix for creating surface-enhanced Raman scattering (SERS) surfaces. Here, we evaluated the SERS activity of PSi with pores ranging in size from meso to macro, the surface of which was coated with gold nanoparticles (Au NPs). We found that different pore diameters in the PSi layers provide different morphology of the gold coating, from an almost monolayer to 50 nm distance between nanoparticles. Methylene blue (MB) and 4-mercaptopyridine (4-MPy) were used to describe the SERS activity of obtained Au/PSi surfaces. The best Raman signal enhancement was shown when the internal diameter of torus-shaped Au NPs is around 35 nm. To understand the role of plasmonic resonances in the observed SERS spectrum, we performed electromagnetic simulations of Raman scattering intensity as a function of the internal diameter. The results of these simulations are consistent with the obtained experimental data.

Novel Ag/Au/Pt trimetallic nanocages used with surface-enhanced Raman scattering for trace fluorescent dye detection

2014 ◽  
Vol 2 (34) ◽  
pp. 5550-5557 ◽  
Author(s):  
Tran Thi Bich Quyen ◽  
Wei-Nien Su ◽  
Ching-Hsiang Chen ◽  
John Rick ◽  
Jyong-Yue Liu ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Hot Spot ◽  
Surface Enhanced Raman Scattering ◽  
Signal Enhancement ◽  
Fluorescent Dye ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Hot Spot Formation ◽  
Spot Formation

Trimetallic nanocages possess inter-metallic synergies among elements and are able to generate significant SERS signal enhancement due to “hot spot” formation.

scholarly journals A Biomedical Surface Enhanced Raman Scattering Substrate: Functionalized Three-Dimensional Porous Membrane Decorated with Silver Nanoparticles

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Li Yuan ◽  
Jinghuai Fang ◽  
Yonglong Jin ◽  
Chaonan Wang ◽  
Tian Xu
Keyword(s):  
Silver Nanoparticles ◽  
Raman Scattering ◽  
Three Dimensional ◽  
Surface Enhanced Raman Scattering ◽  
Porous Membrane ◽  
Raman Signal ◽  
Functional Surface ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

We fabricated a simple, cheap, and functional surface enhanced Raman scattering substrate for biomedical application. Hot spots between two close silver nanoparticles distributed in the skeleton of a three-dimensional porous membrane, especially in the pores, were formed. The dual poles of micropores in the membrane were discussed. The pores could protect the silver nanoparticles in the pores from being oxidized, which makes the membrane effective for a longer period of time. In addition,Staphylococcus aureuscells could be trapped by the micropores and then the Raman signal became stronger, indicating that the functional surface enhanced Raman scattering substrate is reliable.

Finite-Size Effects and Surface-Enhanced Raman Scattering in Noble-Metal Nanoparticles

2004 ◽  
Vol 818 ◽  
Author(s):  
Vitaliy N. Pustovit ◽  
Tigran V. Shahbazyan
Keyword(s):  
Raman Scattering ◽  
Metal Nanoparticles ◽  
Noble Metal ◽  
Finite Size ◽  
Surface Enhanced Raman Scattering ◽  
Noble Metal Nanoparticles ◽  
Raman Signal ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

AbstractWe study the role of a strong electron confinement on the surface-enhanced Raman scattering from molecules adsorbed on small noble-metal nanoparticles. We describe a novel enhancement mechanism which originates from the different effect that confining potential has on s-band and d-band electrons. We demonstrate that the interplay between finite-size and screening efects in the nanoparticle surface layer leads to an enhancement of the surface plasmon local field acting on a molecule located in a close proximity to the metal surface. Our calculations show that the additional enhancement of the Raman signal is especially strong for small nanometer-sized nanoparticles.

scholarly journals Gold Nanofilm-Coated Porous Silicon as Surface-Enhanced Raman Scattering Substrate

2019 ◽  
Vol 9 (22) ◽  
pp. 4806 ◽  
Author(s):  
Ibrahim Khalil ◽  
Chia-Man Chou ◽  
Kun-Lin Tsai ◽  
Steven Hsu ◽  
Wageeh A. Yehye ◽  
...  
Keyword(s):  
Thin Film ◽  
Porous Silicon ◽  
Raman Scattering ◽  
Film Thickness ◽  
Sers Substrate ◽  
Au Film ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Au Thin Film

Metallic film-coated porous silicon (PSi) has been reported as a lucrative surface-enhanced Raman scattering (SERS) substrate. The solution-based fabrication process is facile and easy; however, it requires additional reducing agent and extra chemical treatment, as well as hinders the suitability as a reproducible SERS substrate due to irregular hot spot generation via irregular deposition of metallic nanocrystallites. To address this issue, we report a unique one-step electronic beam (e-beam) physical vapor deposition (PVD) method to fabricate a consistent layer of gold (Au) nanofilm on PSi. Moreover, to achieve the best output as a SERS substrate, PSi prepared by electrochemical etching was used as template to generate an Au layer of irregular surface, offering the surface roughness feature of the PSi–Au thin film. Furthermore, to investigate the etching role and Au film thickness, Au-nanocrystallites of varying thickness (5, 7, and 10 nm) showing discrete surface morphology were characterized and evaluated for SERS effect using Rhodamine 6G (R6G). The SERS signal of R6G adsorbed on PSi–Au thin film showed a marked enhancement, around three-fold enhancement factor (EF), than the Si–Au thin film. The optimal SERS output was obtained for PSi–Au substrate of 7 nm Au film thickness. This study thus indicates that the SERS enhancement relies on the Au film thickness and the roughness feature of the PSi–Au substrate.

scholarly journals Quasi-three-dimension Structured Surface-enhanced Raman Scattering Substrates Based on Silver Nanoparticles/ Porous Silicon Hybrid

2021 ◽  
Author(s):  
Thuy Van Nguyen ◽  
Duc Chinh Vu ◽  
Huy Bui ◽  
Thanh Binh Pham ◽  
Thi Hong Cam Hoang ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Porous Silicon ◽  
Raman Scattering ◽  
Electrochemical Sensors ◽  
Surface Enhanced Raman Scattering ◽  
Sers Substrate ◽  
Three Dimension ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Abstract Surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique for ultrasensitive and selective bio-chemical detection due to its capability of providing “fingerprint” information of molecular structures in low concentrations even at single molecular level. In this work, we present the silver nanoparticles/porous silicon (AgNPs/PSi) hybrid structures as SERS substrates prepared by a fast, straightforward and effective method using the PSi immersion plating in silver nitrate (AgNO3) solution. The nano-silvers can simultaneously grow on the surface and nano-pillars of porous silicon making quasi-three-dimension (quasi-3D) structural SERS substrate that has a large surface area to adsorb moleculars for SERS measurement. The proposed SERS substrate can detect Diphenylamine (DPA) with ultralow concentration of 10-9 M (~0.17 ppb), which would have higher enhancement than 2D surface SERS based on nano-silver deposited on silicon substrate and other electrochemical sensors.

scholarly journals Charge-Transfer Process in Surface-Enhanced Raman Scattering Based on Energy Level Locations of Rare-Earth Nd3+-Doped TiO2 Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2063
Author(s):  
Zihao Zhao ◽  
Xiang Zhao ◽  
Mu Zhang ◽  
Xudong Sun
Keyword(s):  
Rare Earth ◽  
Charge Transfer ◽  
Energy Level ◽  
Raman Scattering ◽  
Signal Intensity ◽  
Raman Signal ◽  
Tio2 Nps ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Surface-enhanced Raman scattering (SERS) for semiconductor nanomaterial systems is limited due to weak Raman signal intensity and unclear charge-transfer (CT) processes for chemical enhancement. Here, rare-earth element neodymium-doped titanium dioxide (Nd-TiO2) nanoparticles (NPs) were synthesized by the sol–gel method. The characterizations show that the doping of Nd ions causes TiO2 NPs to show an increase in the concentration of defects and change in the energy level structure. The CT process between Nd-TiO2 NPs substrate and probe molecule 4-Mercaptopyridine (4-Mpy) was innovatively analyzed using the relative energy level location relationship of the Dorenbos model. The SERS signal intensity exhibits an exponential enhancement with increasing Nd doping concentration and reaches its optimum at 2%, which is attributed to two factors: (1) The increase in the defect concentration is beneficial to the CT process between the TiO2 and the probe molecule; (2) the introduction of 4f electron orbital energy levels of rare-earth ions created unique CT process between Nd3+ and 4-Mpy. Moreover, the Nd-TiO2 NPs substrate shows excellent SERS performance in Raman signal reproducibility (RSD = 5.31%), the limit of detection (LOD = 10−6 M), and enhancement factor (EF = 3.79 × 104). Our work not only improves the SERS performance of semiconductor substrates but also provides a novel approach to the development of selective detection of probe molecules.

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