Journal articles: 'SERS Enhancement Factor'

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Pilot, R., and R. Bozio. "Validation of SERS enhancement factor measurements." Journal of Raman Spectroscopy 49, no. 3 (December 5, 2017): 462–71. http://dx.doi.org/10.1002/jrs.5302.

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Guicheteau, J. A., A. Tripathi, E. D. Emmons, S. D. Christesen, and Augustus W. Fountain. "Reassessing SERS enhancement factors: using thermodynamics to drive substrate design." Faraday Discussions 205 (2017): 547–60. http://dx.doi.org/10.1039/c7fd00141j.

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Over the past 40 years fundamental and application research into Surface-Enhanced Raman Scattering (SERS) has been explored by academia, industry, and government laboratories. To date however, SERS has achieved little commercial success as an analytical technique. Researchers are tackling a variety of paths to help break through the commercial barrier by addressing the reproducibility in both the SERS substrates and SERS signals as well as continuing to explore the underlying mechanisms. To this end, investigators use a variety of methodologies, typically studying strongly binding analytes such as aromatic thiols and azarenes, and report SERS enhancement factor calculations. However a drawback of the traditional SERS enhancement factor calculation is that it does not yield enough information to understand substrate reproducibility, application potential with another analyte, or the driving factors behind the molecule–metal interaction. Our work at the US Army Edgewood Chemical Biological Center has focused on these questions and we have shown that thermodynamic principles play a key role in the SERS response and are an essential factor in future designs of substrates and applications. This work will discuss the advantages and disadvantages of various experimental techniques used to report SERS enhancement with planar SERS substrates and present our alternative SERS enhancement value. We will report on three types of analysis scenarios that all yield different information concerning the effectiveness of the SERS substrate, practical application of the substrate, and finally the thermodynamic properties of the substrate. We believe that through this work a greater understanding for designing substrates will be achieved, one that is based on both thermodynamic and plasmonic properties as opposed to just plasmonic properties. This new understanding and potential change in substrate design will enable more applications for SERS based methodologies including targeting molecules that are traditionally not easily detected with SERS due to the perceived weak molecule–metal interaction of substrates.

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Pál, Petra, Attila Bonyár, Miklós Veres, Laura Juhász, Melinda Szalóki, and István Csarnovics. "An Investigation of Surface-Enhanced Raman Scattering of Different Analytes Adsorbed on Gold Nanoislands." Applied Sciences 11, no. 21 (October 21, 2021): 9838. http://dx.doi.org/10.3390/app11219838.

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In this study, metallic nanoislands were prepared by thermal annealing of gold thin film produced by vacuum evaporation on a glass substrate to investigate the surface-enhanced Raman scattering (SERS) effect on them. The influence of the analyte on the enhancement factor of SERS was studied with riboflavin and rhodamine 6G dye. Two laser excitation sources at 532 and 633 nm wavelengths were used for SERS measurements. We found that the enhancement factors of the gold nanoisland SERS substrates were influenced by the analytes’ adsorption tendency onto their surfaces. The SERS amplification was also found to be dependent on the electronic structure of the molecules; higher enhancement factors were obtained for rhodamine 6G with 532 nm excitation, while for riboflavin the 633 nm source performed better.

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Israelsen, Nathan D., Cynthia Hanson, and Elizabeth Vargis. "Nanoparticle Properties and Synthesis Effects on Surface-Enhanced Raman Scattering Enhancement Factor: An Introduction." Scientific World Journal 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/124582.

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Raman spectroscopy has enabled researchers to map the specific chemical makeup of surfaces, solutions, and even cells. However, the inherent insensitivity of the technique makes it difficult to use and statistically complicated. When Raman active molecules are near gold or silver nanoparticles, the Raman intensity is significantly amplified. This phenomenon is referred to as surface-enhanced Raman spectroscopy (SERS). The extent of SERS enhancement is due to a variety of factors such as nanoparticle size, shape, material, and configuration. The choice of Raman reporters and protective coatings will also influence SERS enhancement. This review provides an introduction to how these factors influence signal enhancement and how to optimize them during synthesis of SERS nanoparticles.

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Sivanesan, Arumugam, Witold Adamkiewicz, Govindasamy Kalaivani, Agnieszka Kamińska, Jacek Waluk, Robert Hołyst, and Emad L. Izake. "Electrochemical pathway for the quantification of SERS enhancement factor." Electrochemistry Communications 49 (December 2014): 103–6. http://dx.doi.org/10.1016/j.elecom.2014.10.007.

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Laurence, Ted A., Gary B. Braun, Norbert O. Reich, and Martin Moskovits. "Robust SERS Enhancement Factor Statistics Using Rotational Correlation Spectroscopy." Nano Letters 12, no. 6 (May 7, 2012): 2912–17. http://dx.doi.org/10.1021/nl3005447.

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Rodrigues, Daniel C., Michele L. de Souza, Klester S. Souza, Diego P. dos Santos, Gustavo F. S. Andrade, and Marcia L. A. Temperini. "Critical assessment of enhancement factor measurements in surface-enhanced Raman scattering on different substrates." Physical Chemistry Chemical Physics 17, no. 33 (2015): 21294–301. http://dx.doi.org/10.1039/c4cp05080k.

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The SERS enhancement factor (SERS-EF) is one of the most important parameters that characterizes the ability of a given substrate to enhance the Raman signal for SERS applications. The comparison between dynamic and static substrates, however, should not be performed in sense of SERS-EF.

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Barbillon, Grégory, Andrey Ivanov, and Andrey K. Sarychev. "Hybrid Au/Si Disk-Shaped Nanoresonators on Gold Film for Amplified SERS Chemical Sensing." Nanomaterials 9, no. 11 (November 8, 2019): 1588. http://dx.doi.org/10.3390/nano9111588.

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We present here the amplification of the surface-enhanced Raman scattering (SERS) signal of nanodisks on a gold film for SERS sensing of small molecules (thiophenol) with an excellent sensitivity. The enhancement is achieved by adding a silicon underlayer for the composition of the nanodisks. We experimentally investigated the sensitivity of the suggested Au/Si disk-shaped nanoresonators for chemical sensing by SERS. We achieved values of enhancement factors of 5 × 10 7 − 6 × 10 7 for thiophenol sensing. Moreover, we remarked that the enhancement factor (EF) values reached experimentally behave qualitatively as those evaluated with the E 4 model.

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He, Shuai, Jefri Chua, Eddie Khay Ming Tan, and James Chen Yong Kah. "Optimizing the SERS enhancement of a facile gold nanostar immobilized paper-based SERS substrate." RSC Advances 7, no. 27 (2017): 16264–72. http://dx.doi.org/10.1039/c6ra28450g.

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Schematic of study to optimize the SERS enhancement factor of a low cost and facile gold nanostar (AuNS)-based paper-SERS substrate through optimizing the paper materials, immobilization strategies, and SERS acquisition conditions.

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Katyal, Jyoti. "Al-Au Heterogeneous Dimer-trimer Nanostructure for SERS." Nanoscience & Nanotechnology-Asia 10, no. 1 (January 23, 2020): 21–28. http://dx.doi.org/10.2174/2210681208666180821141727.

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: Tunability in resonance wavelength and the enhancement of the electromagnetic field intensities around the surface are two unique properties which make metal as a plasmonic material. A theoretical investigation on the LSPR and field enhancement for heterogeneous dimer–trimer metallic nanostructure by constituting Al and Au as two different plamsonic materials has been studied. Since electrons in Al exhibit free behavior for LSPR of Au, therefore, they influence the electric field magnitude generated by Au LSPR. Methods: The electromagnetic simulations reported in this paper were performed using the FDTD Solutions (version 7.5.1), a product of Lumerical Solutions Inc., Vancouver, Canada. We adopted a cubic Yee cell of 1 nm side and a time step Δt= 1.31•10-18 s, bounded by Courant condition. Results: The extinction spectrum shows LSPR peak over UV-visible region for isotropic nanostructure which shifts to NIR region for anisotropic shape nanostructure. The spherical shape hetero dimer nanostructure shows enhancement factor ~ 3.9 X 105 whereas it increases to ~ 6.2 X 106 for anisotropic shape at 610 nm. The field distribution corresponding to the trimer nanostructure reveals a large dipolar field distribution on each of the three nanoparticles, oscillating approximately in-phase. The spherical shape Al-Au-Al shows enhancement factor ~ 8.5 X 106 at 571 nm. The anisotropic shape increase the enhancement factor to ~ 2.4 X 107 at peak wavelength 700 nm i.e. tuning the plasmon wavelength towards NIR region. Conclusion: The tunability in plasmon wavelength and field enhancement factor has been evaluated for heterogeneous nanostructure over wider spectrum range i.e. DUV-Visible-NIR using Au-Al dimer and trimer nanostructure. The isotropic shape Au-Al hetero nanostructure shows larger enhancement in the UV-visible region, whereas the anisotropic shape nanostructure contributes towards the NIR region.

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Mueller, Niclas S., Sebastian Heeg, Patryk Kusch, Etienne Gaufrès, Nathalie Y. W. Tang, Uwe Hübner, Richard Martel, Aravind Vijayaraghavan, and Stephanie Reich. "Plasmonic enhancement of SERS measured on molecules in carbon nanotubes." Faraday Discussions 205 (2017): 85–103. http://dx.doi.org/10.1039/c7fd00127d.

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We isolated the plasmonic contribution to surface-enhanced Raman scattering (SERS) and found it to be much stronger than expected. Organic dyes encapsulated in single-walled carbon nanotubes are ideal probes for quantifying plasmonic enhancement in a Raman experiment. The molecules are chemically protected through the nanotube wall and spatially isolated from the metal, which prevents enhancement by chemical means and through surface roughness. The tubes carry molecules into SERS hotspots, thereby defining molecular position and making it accessible for structural characterization with atomic-force and electron microscopy. We measured a SERS enhancement factor of 10⁶ on α-sexithiophene (6T) molecules in the gap of a plasmonic nanodimer. This is two orders of magnitude stronger than predicted by the electromagnetic enhancement theory (10⁴). We discuss various phenomena that may explain the discrepancy (including hybridization, static and dynamic charge transfer, surface roughness, uncertainties in molecular position and orientation), but found all of them lacking in enhancement for our probe system. We suggest that plasmonic enhancement in SERS is, in fact, much stronger than currently anticipated. We discuss novel approaches for treating SERS quantum mechanically that appear promising for predicting correct enhancement factors. Our findings have important consequences on the understanding of SERS as well as for designing and optimizing plasmonic substrates.

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Kahkhaie, V. Rezaie, M. H. Yousefi, M. Darbani, and A. Mobashery. "Application of Fe-graphene oxide nanocomposite to improve SERS intensity of polyaromatic hydrocarbons-=SUP=-*-=/SUP=-." Журнал технической физики 127, no. 11 (2019): 827. http://dx.doi.org/10.21883/os.2019.11.48522.36-19.

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Abstract Raman spectroscopy is used to provide a structural finger-print by which molecules can be identified. SERS technique offers many orders of magnitude enhancement in initial weak Raman signal of some molecules. To detect Raman signal of pyrene, magnetic properties of iron nanoparticles (Fe NPs) was employed along with graphene oxide (GO). Significant differences were discovered in performance of five different SERS substrates which were prepared using magnetized and non-magnetized Fe NPs-GO nanocomposites (FNRC) and Ag nanoparticles. UV-Vis, Raman and FE-SEM analysis presented complete formation of Ag-NPs, GO and FNRCs. The quantity of enhancement measured showed different enhancements from 1.09 up to 3.54 times for pyrene solution on magnetized Fe NP-GO nanocomposite. SERS enhancement showed a reverse relation with GO/Fe precursor rate. Raman shift suggested formation of new bonds. 2.017 RSD factor presented very fast performance only 10 seconds after irradiation of magnetized FNRCs.

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Liu, Ying, Guangjun Ren, Rongjian Du, Yongming Zhang, Tianbo Tan, Yaqi Wang, and Jianquan Yao. "Study of surface-enhanced Raman scattering of InAs particles of subwavelength apertures at terahertz frequencies." Modern Physics Letters B 29, no. 31 (November 20, 2015): 1550197. http://dx.doi.org/10.1142/s0217984915501973.

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We present a theoretical mechanism for electric field enhancement with SERS of InAs particles of subwavelength apertures under THz excitation. The distribution of electric field confirms that there is a strong enhancement in the InAs particles at THz frequencies. The InAs with a Drude-like behavior in THz range, which is similar to metals at optical frequencies, leads to different SERS when the parameters of these two particles change. The SERS enhancement factor can reach [Formula: see text] under the certain conditions.

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Francis, Mathew K., Binaya Kumar Sahu, P. Balaji Bhargav, Balaji C, Nafis Ahmed, A. Das, and Sandip Dhara. "Ag nanowires based SERS substrates with very high enhancement factor." Physica E: Low-dimensional Systems and Nanostructures 137 (March 2022): 115080. http://dx.doi.org/10.1016/j.physe.2021.115080.

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Xiao, Cheng, Zhibing Chen, Dongxiao Zhang, Wenjian Xiao, Mengze Qing, and Xianhong Liu. "Research on the temperature effect characteristics of SERS enhancement factor." Optik 127, no. 20 (October 2016): 9926–31. http://dx.doi.org/10.1016/j.ijleo.2016.07.079.

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Cara, Eleonora, Luisa Mandrile, Alessio Sacco, Andrea M. Giovannozzi, Andrea M. Rossi, Federica Celegato, Natascia De Leo, et al. "Towards a traceable enhancement factor in surface-enhanced Raman spectroscopy." Journal of Materials Chemistry C 8, no. 46 (2020): 16513–19. http://dx.doi.org/10.1039/d0tc04364h.

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Kneipp, Katrin, Ramachandra R. Dasari, and Yang Wang. "Near-Infrared Surface-Enhanced Raman Scattering (NIR SERS) on Colloidal Silver and Gold." Applied Spectroscopy 48, no. 8 (August 1994): 951–55. http://dx.doi.org/10.1366/0003702944029776.

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Near-infrared surface-enhanced Raman scattering (NIR SERS) was detected with high sensitivity for two model compounds, crystal violet and the DNA base adenine, adsorbed on silver and gold colloidal particles in aqueous solutions. The NIR SERS spectra were measured with a fiber-optic probe with the use of a Ti:sapphire laser at 850 nm as the excitation source and a charge-coupled device (CCD) as the detection system. In a step to achieve the optimal electromagnetic SERS-enhancement conditions, silver and gold sols were modified to shift their extinction spectra more to the NIR region. Surface enhancement factors for both crystal violet and adenine were estimated to be on the order of 106 and 108 for gold and silver, respectively. A larger enhancement factor was observed for adenine with NIR excitation than with visible excitation. The benefits of NIR SERS and its potential applications are discussed.

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Deng, Chao Yue, Gu Ling Zhang, Bin Zou, Hong Long Shi, Yu Jie Liang, Yong Chao Li, Jin Xiang Fu, and Wen Zhong Wang. "Local Electric Field Enhancement of Neighboring Ag Nanoparticles in Surface Enhanced Raman Scattering." Advanced Materials Research 760-762 (September 2013): 801–5. http://dx.doi.org/10.4028/www.scientific.net/amr.760-762.801.

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We used a simple low-temperature hydrothermal approach to synthesize Ag nanoparticles (NPs) and demonstrated their efficiency as organic molecule detectors in surface enhanced Raman Scattering (SERS). Using finite difference time domain simulation, we described an investigation on the distribution of electric fields amplitude of the neighboring Ag NPs. The enhanced electric field is confined at the interparticle gaps and the enhancement factor can be further increased with reducing the spacing between the NPs. The theoretical simulation demonstrated good consistency with the experimental measurement results, which predicts an electric fields amplitude enhancement of 115 at the center of NPs gap and an electromagnetic SERS enhancement of 108. The evidence of clear correlations between SERS enhancement and morphology distribution offer a route to develop more effective SERS substrates.

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Litti, Lucio, and Moreno Meneghetti. "Predictions on the SERS enhancement factor of gold nanosphere aggregate samples." Physical Chemistry Chemical Physics 21, no. 28 (2019): 15515–22. http://dx.doi.org/10.1039/c9cp02015b.

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Shinki, Jaspreet Singh, and Subhendu Sarkar. "Tuning the topographical parameters of Si pyramids for a better surface enhanced Raman response." Physical Chemistry Chemical Physics 23, no. 46 (2021): 26407–16. http://dx.doi.org/10.1039/d1cp03576b.

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Development of facile routes for the fabrication of surface enhanced Raman substrates (SERS) along with optimal conditions for a high enhancement factor are significant from an application perspective of SERS.

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Wang, Zhong, Kesu Cai, Yang Lu, Haining Wu, Yuee Li, and Qingguo Zhou. "Insight into the working wavelength of hotspot effects generated by popular nanostructures." Nanotechnology Reviews 8, no. 1 (May 17, 2019): 24–34. http://dx.doi.org/10.1515/ntrev-2019-0003.

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Abstract A proper excitation wavelength is much important for the application of surface-enhanced Raman spectroscopy (SERS) in the biochemical field. Here, based on a SERS substrate model with an incident Gaussian beam, we investigate the dependence of the electric field enhancement on the incident wavelength of the excitation laser for popular nanostructures, including nanosphere dimer, nanorod dimer, and nanorod arrays. The results in the present manuscript indicate that both the nanosphere and nanorod dimer present a much broader plasmonic excitation wavelength range extending to the near-infrared region. The enhancement effect of Nanorod arrays is strongly dependent on the incident direction of excitation light. Finally, according to the conclusions above, a SERS substrate consisting of nanocubes based on the SPP eigen-mode is proposed and the electric field enhancement is homogeneous, and insensitive to the polarization of the incident laser. The enhancement factor is not ultrahigh; however, good homogeneousness permits for quantitative detection of lower concentration components in mixtures. Graphical abstract: By investigating the dependence of the electric field enhancement on the incident wavelength of the excitation laser for popular nanostructures, we propose a SERS substrate consisting of Au nanocubes based on the SPP eigenmode. The electric field enhancement is homogeneous, and insensitive to the polarization of the incident laser. Though the enhancement factor is not ultrahigh, good homogeneousness permits for quantitative detection of lower concentration components in mixtures.

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Lay, Chee Leng, Charlynn Sher Lin Koh, Jing Wang, Yih Hong Lee, Ruibin Jiang, Yijie Yang, Zhe Yang, In Yee Phang, and Xing Yi Ling. "Aluminum nanostructures with strong visible-range SERS activity for versatile micropatterning of molecular security labels." Nanoscale 10, no. 2 (2018): 575–81. http://dx.doi.org/10.1039/c7nr07793a.

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A ciphertext-embedded machine-readable micro-QR code is constructed using structurally uniform visible-range SERS-active Al nanostructures with an average SERS enhancement factor of >10⁴.

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Huang, Chu-Yu, and Ming-Shiuan Tsai. "Tunable Silver Nanoparticle Arrays by Hot Embossing and Sputter Deposition for Surface-Enhanced Raman Scattering." Applied Sciences 9, no. 8 (April 19, 2019): 1636. http://dx.doi.org/10.3390/app9081636.

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Surface-enhanced Raman scattering (SERS) spectroscopy has attracted a lot of attention over the past 30 years. Due to its extreme sensitivity and label-free detection capability, it has shown great potential in areas such as analytical chemistry, biochemistry, and environmental science. However, the major challenge is to manufacture large-scale highly SERS active substrates with high controllability, good reproducibility, and low cost. In this study, we report a novel method to fabricate uniform silver nanoparticle arrays with tunable particle sizes and interparticle gaps. Using hot embossing and sputtering techniques, we were able to batch produce the silver nanoparticle arrays SERS active substrate with consistent quality and low cost. We showed that the proposed SERS active substrate has good uniformity and high reproducibility. Experimental results show that the SERS enhancement factor is affected by silver nanoparticles size and interparticle gaps. Furthermore, the enhancement factor of the SERS signal obtained from Rhodamine 6G (R6G) probe molecules was as high as 1.12 × 107. Therefore, the developed method is very promising for use in many SERS applications.

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Youssef, Ali Ahmed, Aseel Adel Chasb, and Alwan Mohamed Alwan. "Improved Bacterial Detection Limit via Wet KOH Etching Pathway Enhanced by Laser." Journal of Physics: Conference Series 2322, no. 1 (August 1, 2022): 012073. http://dx.doi.org/10.1088/1742-6596/2322/1/012073.

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Abstract Laser with a fixed wavelength (405nm) at different values of intensities (50, 100, 150, 200 mW/cm2) were used to re synthesis Si nano- pillars as based SERS active substrates. The idea was to form SERS devices with high enhancement factor to sense the low residence of bacteria. The results exposed that the topographical features of the Si nano-pillars layer and so, the performance of SERS sensor could be well- controlled via the adjusting of laser intensity through the laser assisted Wet KOH process. The SERS sensing of low concentrations of shows highest bacterial enhancement factor (E.F = 30.1 × 105) and minimum detection limit (LOD = 3.30 Cfu/ml) were realized from high altitude Si nano- pillars; partly populated with three dimensions AgNPs layer, and the use of 150 mW/cm2 laser power density.

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Chen, Kuan-Hung, Meng-Ju Pan, Zoljargal Jargalsaikhan, Tseren-Onolt Ishdorj, and Fan-Gang Tseng. "Development of Surface-Enhanced Raman Scattering (SERS)-Based Surface-Corrugated Nanopillars for Biomolecular Detection of Colorectal Cancer." Biosensors 10, no. 11 (October 31, 2020): 163. http://dx.doi.org/10.3390/bios10110163.

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In this paper, a nanobiosensor with surface-enhanced Raman scattering (SERS) capability is introduced for highly sensitive miRNA detection in colorectal cancer. This sensor was designed and fabricated by employing a nanoshielding mechanism from nanopolystyrene beads to resist reactive ion etching and allow anisotropic electrochemical etching, producing high-aspect-ratio, surface-corrugated nanopillars (SiNPs) on a silicon wafer to create extensive hot spots along the nanopillars for improved SERS signals. SERS enhancements were correlated with nanorange roughness, indicating that hot spots along the pillars were the crucial factor to improve the SERS effect. We achieved the detection capability of a trace amount of R6G (10−8 M), and the SERS signal enhancement factor (EF) was close to 1.0 × 107 on surface-corrugated gold SiNPs. miRNA samples were also demonstrated on this sensor with good sensitivity and specificity. The target molecule miR-21-Cy5 was easily monitored through Raman spectrum variation with a PCR-comparable concentration at around 100 pM with clear nucleotide-specific Raman signals, which is also suitable for biomolecule sensing.

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Hong, Seongmin, and Xiao Li. "Optimal Size of Gold Nanoparticles for Surface-Enhanced Raman Spectroscopy under Different Conditions." Journal of Nanomaterials 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/790323.

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Gold nanoparticles have been used as effective surface-enhanced Raman spectroscopy (SERS) substrates for decades. However, the origin of the enhancement and the effect of the size of nanoparticles still need clarification. Here, gold nanoparticles with different sizes from 17 to 80 nm were synthesized and characterized, and their SERS enhancement toward both 4-aminothiophenol and 4-nitrothiophenol was examined. For the same number of nanoparticles, the enhancement factor generated from the gold nanoparticles increases as the size of nanoparticles increases. Interestingly, when the concentration of gold or the total surface area of gold nanoparticles was kept the same, the optimal size of gold nanoparticles was found out to be around 50 nm when the enhancement factor reached a maximum. The same size effect was observed for both 4-aminothiophenol and 4-nitrothiophenol, which suggests that the conclusions drawn in this study might also be applicable to other adsorbates during SERS measurements.

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Jabłońska, Anna, Aleksandra Jaworska, Mateusz Kasztelan, Sylwia Berbeć, and Barbara Pałys. "Graphene and Graphene Oxide Applications for SERS Sensing and Imaging." Current Medicinal Chemistry 26, no. 38 (January 3, 2019): 6878–95. http://dx.doi.org/10.2174/0929867325666181004152247.

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: Surface Enhanced Raman Spectroscopy (SERS) has a long history as an ultrasensitive platform for the detection of biological species from small aromatic molecules to complex biological systems as circulating tumor cells. Thanks to unique properties of graphene, the range of SERS applications has largely expanded. Graphene is efficient fluorescence quencher improving quality of Raman spectra. It contributes also to the SERS enhancement factor through the chemical mechanism. In turn, the chemical flexibility of Reduced Graphene Oxide (RGO) enables tunable adsorption of molecules or cells on SERS active surfaces. Graphene oxide composites with SERS active nanoparticles have been also applied for Raman imaging of cells. This review presents a survey of SERS assays employing graphene or RGO emphasizing the improvement of SERS enhancement brought by graphene or RGO. The structure and physical properties of graphene and RGO will be discussed too.

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Indrasekara, A. S. D. S., S. Meyers, S. Shubeita, L. C. Feldman, T. Gustafsson, and L. Fabris. "Gold nanostar substrates for SERS-based chemical sensing in the femtomolar regime." Nanoscale 6, no. 15 (2014): 8891–99. http://dx.doi.org/10.1039/c4nr02513j.

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A SERS sensor based on gold nanostars is described. The size and sharpness of the nanostar spikes are tuned to maximize sensitivity and SERS enhancement, yielding a detection limit of 10⁻¹⁵ M and an enhancement factor of 10⁹. The effectiveness of the sensor is proven for both chemisorbed and physisorbed analytes under non-resonant conditions and its multiplexing capability is demonstrated.

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Atanasov, Petar A., Nikolay N. Nedyalkov, Naoki Fukata, Wipakorn Jevasuwan, and Thiyagu Subramani. "Surface-Enhanced Raman Spectroscopy (SERS) of Neonicotinoid Insecticide Thiacloprid Assisted by Silver and Gold Nanostructures." Applied Spectroscopy 74, no. 3 (November 25, 2019): 357–64. http://dx.doi.org/10.1177/0003702819878267.

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This study expresses our results on surface-enhanced Raman spectroscopy (SERS) analyses of neonicotinoid insecticide thiacloprid, i.e., Calypso 480 SC, in quantities much smaller than usually applied in the agricultural medicine. Advanced Ag and Au nanostructures created by the thermal deposition technique on Al2O3 ceramic were applied as active substrates for SERS analyses. The minimum concentration of thiacloprid detected was 380 µM and the enhancement factor was estimated to be about 3 × 103. The intensity of the SERS peaks increased by an order of magnitude after pulsed laser annealing of the films and formation of nanoparticle arrays and the enhancement factor reached ≈104, respectively. The proposed study has direct bearing on the environment and human health by detection of small amounts or residue of harmful pollutants using a relatively cheap and easy method to produce active SERS substrates.

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Budner, Bogusław, Mariusz Kuźma, Barbara Nasiłowska, Bartosz Bartosewicz, Malwina Liszewska, and Bartłomiej J. Jankiewicz. "Fabrication of silver nanoisland films by pulsed laser deposition for surface-enhanced Raman spectroscopy." Beilstein Journal of Nanotechnology 10 (April 16, 2019): 882–93. http://dx.doi.org/10.3762/bjnano.10.89.

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The results of studies on the fabrication and characterization of silver nanoisland films (SNIFs) using pulsed laser deposition (PLD) and the evaluation of these films as potential surface-enhanced Raman scattering (SERS) substrates are reported. The SNIFs with thicknesses in a range of 4.7 ± 0.2 nm to 143.2 ± 0.2 nm were deposited under different conditions on silicon substrates. Size and morphology of the fabricated silver nanoislands mainly depend on the substrate temperature, and number and energy of the laser pulses. SERS properties of the fabricated films were evaluated by measuring SERS spectra of para-mercaptoaniline (pMA) molecules adsorbed on them. SERS enhancement factors are shown to depend on the SNIF morphology, which is modified by changes of the deposition conditions. The highest enhancement factor in the range of 105 was achieved for SNIFs that have oval and circular silver nanoislands with small distances between them.

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Ramos, Iván A., L. M. León Hilario, María L. Pedano, and Andres A. Reynoso. "Geometry-induced enhancement factor improvement in covered-gold-nanorod-dimer antennas." RSC Advances 11, no. 16 (2021): 9518–27. http://dx.doi.org/10.1039/d1ra00285f.

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Designs with gold covering far from the gap area applied on nanorod-dimer antennas can enable hybrid electrical and SERS detection. Simulations show promising and robust increasement of the enhancement factor with respect to the uncovered dimer.

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Huang, Chu-Yu, and Chih-Hung Chien. "Facile Fabrication of Micro/Nano Hierarchical SERS Sensor via Anisotropic Etching and Electrochemical Treatment for Malachite Green Detection." Applied Sciences 9, no. 23 (December 2, 2019): 5237. http://dx.doi.org/10.3390/app9235237.

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We propose a facile method to produce micro/nano hierarchical surface-enhanced Raman scattering (SERS) active substrates using simple steps and inexpensive costs. The proposed SERS substrate is a silicon pyramid array covered by a nanostructured gold film (AuNS @ SiPA). Through finite element method (FEM) simulation, we showed that many strong local electric field enhancements (hot spots) were formed between the nano-gap of gold nanostructures. In addition, the micron-scale pyramid structure not only increases the sensing surface area of the sensor, but also helps trap light. By combining these micro and nano structures, the proposed micro/nano hierarchical SERS sensor exhibited high sensitivity. Experimental results confirmed that the AuNS @ SiPA substrate has high sensitivity. The SERS signal enhancement factor obtained from the Rhodamine 6G (R6G) probe molecules was as high as 1 × 107 and the SERS substrates were found to be able to detect a very low concentration of 0.01 nM malachite green (MG) solution. Therefore, this study provides a novel and practical method for fabricating SERS substrates that can facilitate the use of SERS in medicine, food safety, and biotechnology.

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Gao, Jun, Huan Qian, Shang Xu, and Min Han. "Investigation of 1D Siliver Nanoparticle Arrays for Use as Molecule Concentration-Specific SERS Substrates." Journal of Nanomaterials 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/989803.

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One-dimensional arrays of silver nanoparticles with a particle size of 10.5 nm and interparticle spacing of 8.5 nm were fabricated by depositing nanoparticles in gas phase on block copolymer self-assembled templates. The substrate showed a surface-enhanced Raman scattering (SERS) enhancement factor as high as1×107with good reproducibility and stability. The dependence of the average enhancement factor and the SERS intensity on the packing density of the analyte molecules were investigated. For a tiny amount of analytes in the range of1×10-14to3×10-13 mol/mm2, the SERS signal showed a linear dependence on the molecule packing density on a logarithmic scale, with a slope of about 1.25. The substrates are promising for quantitative detection of trace level molecules.

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Tastekova, Elina A., Alexander Yu Polyakov, Anastasia E. Goldt, Alexander V. Sidorov, Alexandra A. Oshmyanskaya, Irina V. Sukhorukova, Dmitry V. Shtansky, Wolgang Grünert, and Anastasia V. Grigorieva. "Facile chemical routes to mesoporous silver substrates for SERS analysis." Beilstein Journal of Nanotechnology 9 (March 14, 2018): 880–89. http://dx.doi.org/10.3762/bjnano.9.82.

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Mesoporous silver nanoparticles were easily synthesized through the bulk reduction of crystalline silver(I) oxide and used for the preparation of highly porous surface-enhanced Raman scattering (SERS)-active substrates. An analogous procedure was successfully performed for the production of mesoporous silver films by chemical reduction of oxidized silver films. The sponge-like silver blocks with high surface area and the in-situ-prepared mesoporous silver films are efficient as both analyte adsorbents and Raman signal enhancement mediators. The efficiency of silver reduction was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The developed substrates were applied for SERS detection of rhodamine 6G (enhancement factor of about 1–5 × 105) and an anti-ischemic mildronate drug (meldonium; enhancement factor of ≈102) that is known for its ability to increase the endurance performance of athletes.

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Kang, Hyun Wook, Juyoung Leem, and Hyung Jin Sung. "Photoinduced synthesis of Ag nanoparticles on ZnO nanowires for real-time SERS systems." RSC Advances 5, no. 1 (2015): 51–57. http://dx.doi.org/10.1039/c4ra11296b.

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Hierarchical nanostructure of Ag nanoparticles on ZnO nanowires is introduced by using a photoinduced synthesis. A real-time, in situ SERS detection system is achieved with a microfluidic channel. The hierarchical nanostructure shows 6.36 × 10¹¹ of SERS enhancement factor.

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36

Lin, Shusen, Rutuja Mandavkar, Shalmali Burse, Md Ahasan Habib, Tasmia Khalid, Mehedi Hasan Joni, Young-Uk Chung, Sundar Kunwar, and Jihoon Lee. "MoS2 Nanoplatelets on Hybrid Core-Shell (HyCoS) AuPd NPs for Hybrid SERS Platform for Detection of R6G." Nanomaterials 13, no. 4 (February 18, 2023): 769. http://dx.doi.org/10.3390/nano13040769.

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In this work, a novel hybrid SERS platform incorporating hybrid core-shell (HyCoS) AuPd nanoparticles (NPs) and MoS2 nanoplatelets has been successfully demonstrated for strong surface-enhanced Raman spectroscopy (SERS) enhancement of Rhodamine 6G (R6G). A significantly improved SERS signal of R6G is observed on the hybrid SERS platform by adapting both electromagnetic mechanism (EM) and chemical mechanism (CM) in a single platform. The EM enhancement originates from the unique plasmonic HyCoS AuPd NP template fabricated by the modified droplet epitaxy, which exhibits strong plasmon excitation of hotspots at the nanogaps of metallic NPs and abundant generation of electric fields by localized surface plasmon resonance (LSPR). Superior LSPR results from the coupling of distinctive AuPd core-shell NP and high-density background Au NPs. The CM enhancement is associated with the charge transfer from the MoS2 nanoplatelets to the R6G. The direct contact via mixing approach with optimal mixing ratio can effectively facilitate the charges transfer to the HOMO and LUMO of R6G, leading to the orders of Raman signal amplification. The enhancement factor (EF) for the proposed hybrid platform reaches ~1010 for R6G on the hybrid SERS platform.

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37

Dai, Pei, Haochen Li, Xianzhi Huang, Nan Wang, and Lihua Zhu. "Highly Sensitive and Stable Copper-Based SERS Chips Prepared by a Chemical Reduction Method." Nanomaterials 11, no. 10 (October 19, 2021): 2770. http://dx.doi.org/10.3390/nano11102770.

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Cu chips are cheaper than Ag and Au chips for practical SERS applications. However, copper substrates generally have weak SERS enhancement effects and poor stability. In the present work, Cu-based SERS chips with high sensitivity and stability were developed by a chemical reduction method. In the preparation process, Cu NPs were densely deposited onto fabric supports. The as-prepared Cu-coated fabric was hydrophobic with fairly good SERS performance. The Cu-coated fabric was able to be used as a SERS chip to detect crystal violet, and it exhibited an enhancement factor of 2.0 × 106 and gave a limit of detection (LOD) as low as 10–8 M. The hydrophobicity of the Cu membrane on the fabric is favorable to cleaning background interference signals and promoting the stability of Cu NPs to environment oxidation. However, this Cu SERS chip was still poor in its long-term stability. The SERS intensity on the chip was decreased to 18% of the original one after it was stored in air for 60 days. A simple introduction of Ag onto the clean Cu surface was achieved by a replacement reaction to further enhance the SERS performances of the Cu chips. The Ag-modified Cu chips showed an increase of the enhancement factor to 7.6 × 106 due to the plasmonic coupling between Cu and Ag in nanoscale, and decreased the LOD of CV to 10–11 M by three orders of magnitude. Owing to the additional protection of Ag shell, the SERS intensity of the Cu-Ag chip after a two-month storing maintained 80% of the original intensity. The Cu-Ag SERS chips were also applied to detect other organics, and showing wide linearity range and low LOD values for the quantitative detection.

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Xia, Tianyu, Hu Luo, Shouguo Wang, Jialong Liu, Guanghua Yu, and Rongming Wang. "Large-scale synthesis of gold dendritic nanostructures for surface enhanced Raman scattering." CrystEngComm 17, no. 22 (2015): 4200–4204. http://dx.doi.org/10.1039/c5ce00407a.

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A precisely controlled FIB technique is used to fabricate Au dendritic nanostructures on a large scale. These Au dendritic nanostructures exhibit excellent SERS properties with a low concentration of RhB as the target molecule and the enhancement factor of SERS reaches 10⁷.

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Zhang, Jingran, Tianqi Jia, Yongda Yan, Li Wang, Peng Miao, Yimin Han, Xinming Zhang, et al. "Label-free highly sensitive probe detection with novel hierarchical SERS substrates fabricated by nanoindentation and chemical reaction methods." Beilstein Journal of Nanotechnology 10 (December 13, 2019): 2483–96. http://dx.doi.org/10.3762/bjnano.10.239.

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Nanostructures have been widely employed in surface-enhanced Raman scattering (SERS) substrates. Recently, in order to obtain a higher enhancement factor at a lower detection limit, hierarchical structures, including nanostructures and nanoparticles, appear to be viable SERS substrate candidates. Here we describe a novel method integrating the nanoindentation process and chemical redox reaction to machine a hierarchical SERS substrate. The micro/nanostructures are first formed on a Cu(110) plane and then Ag nanoparticles are generated on the structured copper surface. The effect of the indentation process parameters and the corrosion time in the AgNO3 solution on the Raman intensities of the SERS substrate with hierarchical structures are experimentally studied. The intensity and distribution of the electric field of single and multiple Ag nanoparticles on the surface of a plane and with multiple micro/nanostructures are studied with COMSOL software. The feasibility of the hierarchical SERS substrate is verified using R6G molecules. Finally, the enhancement factor using malachite green molecules was found to reach 5.089 × 109, which demonstrates that the production method is a simple, reproducible and low-cost method for machining a highly sensitive, hierarchical SERS substrate.

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Alexander, Kristen D., Shunping Zhang, Angela R. Hight Walker, Hongxing Xu, and Rene Lopez. "Relationship between Length and Surface-Enhanced Raman Spectroscopy Signal Strength in Metal Nanoparticle Chains: Ideal Models versus Nanofabrication." Journal of Nanotechnology 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/840245.

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We have employed capillary force deposition on ion beam patterned substrates to fabricate chains of 60 nm gold nanospheres ranging in length from 1 to 9 nanoparticles. Measurements of the surface-averaged SERS enhancement factor strength for these chains were then compared to the numerical predictions. The SERS enhancement conformed to theoretical predictions in the case of only a few chains, with the vast majority of chains tested not matching such behavior. Although all of the nanoparticle chains appear identical under electron microscope observation, the extreme sensitivity of the SERS enhancement to nanoscale morphology renders current nanofabrication methods insufficient for consistent production of coupled nanoparticle chains. Notwithstanding this fact, the aggregate data also confirmed that nanoparticle dimers offer a large improvement over the monomer enhancement while conclusively showing that, within the limitations imposed by current state-of-the-art nanofabrication techniques, chains comprising more than two nanoparticles provide only a marginal signal boost over the already considerable dimer enhancement.

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Hackett, L. P., L. L. Goddard, and G. L. Liu. "Plasmonic nanocone arrays for rapid and detailed cell lysate surface enhanced Raman spectroscopy analysis." Analyst 142, no. 23 (2017): 4422–30. http://dx.doi.org/10.1039/c7an00630f.

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Jian, Ye, and VanDorpe Pol. "Nanocrosses with Highly Tunable Double Resonances for Near-Infrared Surface-Enhanced Raman Scattering." International Journal of Optics 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/745982.

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We present asymmetric gold nanocrosses with highly tunable double resonances for the near-infrared (NIR) surface-enhanced Raman scattering (SERS), optimizing electric field enhancement at both the excitation and Stokes Raman wavelengths. The calculated largest SERS enhancement factor can reach a value as large as1.0×1010. We have found that the peak separation, the resonance position, and peak intensity ratio of the double-resonance gold nanocrosses can be tuned by changing the structural dimensions or the light polarization.

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Caro, Carlos, Pedro Quaresma, Eulália Pereira, Jaime Franco, Manuel Pernia Leal, Maria García-Martín, Jose Royo, et al. "Synthesis and Characterization of Elongated-Shaped Silver Nanoparticles as a Biocompatible Anisotropic SERS Probe for Intracellular Imaging: Theoretical Modeling and Experimental Verification." Nanomaterials 9, no. 2 (February 13, 2019): 256. http://dx.doi.org/10.3390/nano9020256.

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Progress in the field of biocompatible SERS nanoparticles has promising prospects for biomedical applications. In this work, we have developed a biocompatible Raman probe by combining anisotropic silver nanoparticles with the dye rhodamine 6G followed by subsequent coating with bovine serum albumin. This nanosystem presents strong SERS capabilities in the near infrared (NIR) with a very high (2.7 × 107) analytical enhancement factor. Theoretical calculations reveal the effects of the electromagnetic and chemical mechanisms in the observed SERS effect for this nanosystem. Finite element method (FEM) calculations showed a considerable near field enhancement in NIR. Using density functional quantum chemical calculations, the chemical enhancement mechanism of rhodamine 6G by interaction with the nanoparticles was probed, allowing us to calculate spectra that closely reproduce the experimental results. The nanosystem was tested in cell culture experiments, showing cell internalization and also proving to be completely biocompatible, as no cell death was observed. Using a NIR laser, SERS signals could be detected even from inside cells, proving the applicability of this nanosystem as a biocompatible SERS probe.

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44

Wu, Hao, Hua Wang, and Guanghai Li. "Metal oxide semiconductor SERS-active substrates by defect engineering." Analyst 142, no. 2 (2017): 326–35. http://dx.doi.org/10.1039/c6an01959e.

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An effective electric current model based on defect engineering is proposed, and by applying this model, α-MoO₃, a non-SERS or weak SERS, active substrate, can be transformed into a SERS-active substrate with an enhancement factor as high as 1.8 × 10⁷ and a detection limit of 10⁻⁸ M for R6G. This model can be used to predict the SERS performance of other metal oxide semiconductors.

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Etchegoin, P. G., E. C. Le Ru, R. C. Maher, and L. F. Cohen. "Enhancement factor averaging and the photostability of probes in SERS vibrational pumping." Physical Chemistry Chemical Physics 9, no. 35 (2007): 4923. http://dx.doi.org/10.1039/b706395d.

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46

Yi, Mingyue, Yu Zhang, Jiawen Xu, Dingyuan Deng, Zhu Mao, Xiangchun Meng, Xiumin Shi, and Bing Zhao. "Surface-Enhanced Raman Scattering Activity of ZrO2 Nanoparticles: Effect of Tetragonal and Monoclinic Phases." Nanomaterials 11, no. 9 (August 24, 2021): 2162. http://dx.doi.org/10.3390/nano11092162.

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The effect of the ZrO2 crystal form on surface-enhanced Raman scattering (SERS) activity was studied. The ratio of the tetragonal (T) and monoclinic (M) phases of ZrO2 nanoparticles (ZrO2 NPs) was controlled by regulating the ratio of two types of additives in the hydrothermal synthesis method. The SERS intensity of 4-mercaptobenzoic acid (4–MBA) was gradually enhanced by changing the M and T phase ratio in ZrO2 NPs. The degree of charge transfer (CT) in the enhanced 4–MBA molecule was greater than 0.5, indicating that CT was the main contributor to SERS. The intensity of SERS was strongest when the ratio of the T crystal phase in ZrO2 was 99.7%, and the enhancement factor reached 2.21 × 104. More importantly, the proposed study indicated that the T and M phases of the ZrO2 NPs affected the SERS enhancement. This study provides a new approach for developing high-quality SERS substrates and improving the transmission efficiency of molecular sensors.

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Chang, Tung-Hao, Yun-Ting Liu, Yu-Cheng Chang, and An-Ya Lo. "Fabrication of Three-Dimensional ZnO: Ga@ITO@Ag SERS-Active Substrate for Sensitive and Repeatable Detectability." Nanomaterials 13, no. 1 (December 29, 2022): 163. http://dx.doi.org/10.3390/nano13010163.

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Vertically aligned ZnO: Ga nanotowers can be directly synthesized on a glass substrate with a ZnO seed film via the chemical bath method. A novel heterostructure of ZnO: Ga@ITO@Ag nanotowers was subsequently deposited in the ITO layer and Ag nanoparticles via the facile two-step ion-sputtering processes on the ZnO: Ga nanotowers. The appropriate ion-sputtering times of the ITO layer and Ag nanoparticles can benefit the fabrication of ZnO: Ga@ITO@Ag nanotowers with higher surface-enhanced Raman scattering (SERS) enhancement in detecting rhodamine 6G (R6G) molecules. Compared with ZnO: Ga@Ag nanotowers, ZnO: Ga@ITO@Ag nanotowers exhibited a high SERS enhancement factor of 2.25 × 108 and a lower detection limit (10−14 M) for detecting R6G molecules. In addition, the ITO layer used as an intermediate layer between ZnO: Ga nanotowers and Ag nanoparticles can improve SERS enhancement, sensitivity, uniformity, reusability, detection limit, and stability for detecting amoxicillin molecules. This phenomenon shall be ascribed to the ITO layer exhibiting a synergistic Raman enhancement effect through interfacial charge transfer for enhancing SERS activity. As a result, ZnO: Ga@ITO@Ag nanotowers can construct a three-dimensional SERS substrate for potential applications in environmentally friendly and cost-effective chemical or drug detection.

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Chang, Tung-Hao, Hsin-Wei Di, Yu-Cheng Chang, and Chia-Man Chou. "Ag Nanoparticles Decorated CuO@RF Core-Shell Nanowires for High-Performance Surface-Enhanced Raman Spectroscopy Application." Molecules 27, no. 23 (December 2, 2022): 8460. http://dx.doi.org/10.3390/molecules27238460.

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Vertical-aligned CuO nanowires have been directly fabricated on Cu foil through a facile thermal oxidation process by a hotplate at 550 °C for 6 h under ambient conditions. The intermediate layer of resorcinol–formaldehyde (RF) and silver (Ag) nanoparticles can be sequentially deposited on Cu nanowires to form CuO@RF@Ag core-shell nanowires by a two-step wet chemical approach. The appropriate resorcinol weight and silver nitrate concentration can be favorable to grow the CuO@RF@Ag nanowires with higher surface-enhanced Raman scattering (SERS) enhancement for detecting rhodamine 6G (R6G) molecules. Compared with CuO@Ag nanowires grown by ion sputtering, CuO@RF@Ag nanowires exhibited a higher SERS enhancement factor of 5.33 × 108 and a lower detection limit (10−12 M) for detecting R6G molecules. This result is ascribed to the CuO@RF@Ag nanowires with higher-density hot spots and surface-active sites for enhanced high SERS enhancement, good reproducibility, and uniformity. Furthermore, the CuO@RF@Ag nanowires can also reveal a high-sensitivity SERS-active substrate for detecting amoxicillin (10−10 M) and 5-fluorouracil (10−7 M). CuO@RF@Ag nanowires exhibit a simple fabrication process, high SERS sensitivity, high reproducibility, high uniformity, and low detection limit, which are helpful for the practical application of SERS in different fields.

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Khalil, Ibrahim, Chia-Man Chou, Kun-Lin Tsai, Steven Hsu, Wageeh A. Yehye, and Vincent K. S. Hsiao. "Gold Nanofilm-Coated Porous Silicon as Surface-Enhanced Raman Scattering Substrate." Applied Sciences 9, no. 22 (November 10, 2019): 4806. http://dx.doi.org/10.3390/app9224806.

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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.

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Yoon, Daesung, Songhwa Chae, Wook Kim, Donghun Lee, and Dukhyun Choi. "Superhydrophobic plasmonic nanoarchitectures based on aluminum hydroxide nanotemplates." Nanoscale 10, no. 36 (2018): 17125–30. http://dx.doi.org/10.1039/c8nr04873h.

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Journal articles on the topic 'SERS Enhancement Factor'

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