Dataset Information

Quantification and coupling of the electromagnetic and chemical contributions in surface-enhanced Raman scattering.

ABSTRACT: In surface-enhanced Raman scattering (SERS), both chemical (CE) and electromagnetic (EM) field effects contribute to its overall enhancement. However, neither the quantification of their relative contributions nor the substrate dependence of the chemical effect have been well established. Moreover, there is to date no understanding of a possible coupling between both effects. Here we demonstrate how systematically engineered silver and gold planar and nanostructured substrates, covering a wide range of field enhancements, provide a way to determine relative contributions of chemical and electromagnetic field-enhancement in SERS measurements of benzenethiol. We find a chemical enhancement of 2 to 14 for different vibrational resonances when referencing against a vibrational mode that undergoes minimal CE. The values are independent of substrate type and independent of the enhancement of the electromagnetic intensity in the range from 1 to 10⁶. This absence of correlation between chemical and electromagnetic enhancement resolves several long-standing controversies on substrate and intensity dependence of the chemical enhancement and allows for a more systematic design of SERS substrates with desired properties.

SUBMITTER: Su Y

PROVIDER: S-EPMC6404390 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Publications

Quantification and coupling of the electromagnetic and chemical contributions in surface-enhanced Raman scattering.

Su Yarong Y Shi Yuanzhen Y Wang Ping P Du Jinglei J Raschke Markus B MB Pang Lin L

Beilstein journal of nanotechnology 20190225

In surface-enhanced Raman scattering (SERS), both chemical (CE) and electromagnetic (EM) field effects contribute to its overall enhancement. However, neither the quantification of their relative contributions nor the substrate dependence of the chemical effect have been well established. Moreover, there is to date no understanding of a possible coupling between both effects. Here we demonstrate how systematically engineered silver and gold planar and nanostructured substrates, covering a wide r ...[more]

PMID: 30873327

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Project description:Azo compounds such as the Sudan dyes I-IV are frequently used illegally as colorants and added to a wide range of foods. These compounds have been linked to a number of food safety hazards. Several methods have been proposed to detect food contamination by azo compounds and most of these are laboratory based; however, the development of reliable and portable methods for the detection and quantification of food contaminated by these chemicals in low concentration is still needed due to their potentially carcinogenic properties. In this study, we investigated the ability of surface enhanced Raman scattering (SERS) combined with chemometrics to quantify Sudan I-IV dyes. SERS spectra were acquired using a portable Raman device and gold nanoparticles were employed as the SERS substrate. As these dyes are hydrophobic, they were first dissolved in water: acetonitrile (1:10, v/v) as single Sudan dyes (I-IV) at varying concentrations. SERS was performed at 785 nm and the spectra were analyzed by using partial least squares regression (PLS-R) with double cross-validations. The coefficient of determination (Q2) were 0.9286, 0.9206, 0.8676 and 0.9705 for Sudan I to IV, respectively; the corresponding limits of detection (LOD) for these dyes were estimated to be 6.27 × 10-6, 5.35 × 10-5, 9.40 × 10-6 and 1.84 × 10-6 M. Next, quadruplex mixtures were made containing all four Sudan dyes. As the number of possible combinations needed to cover the full concentration range at 5% intervals would have meant collecting SERS spectra from 194,481 samples (214 combinations) we used a sustainable solution based on Latin hypercubic sampling and reduced the number of mixtures to be analyzed to just 90. After collecting SERS spectra from these mixture PLS-R models with bootstrapping validations were employed. The results were slightly worse in which the Q2 for Sudan I to IV were 0.8593, 0.7255, 0.5207 and 0.5940 when PLS1 models (i.e., one model for one dye) was employed and they changed to 0.8329, 0.7288, 0.5032 and 0.5459 when PLS2 models were employed (i.e., four dyes were modelled simultaneously). These results showed the potential of SERS to be used as a high-throughput, low-cost, and reliable methods for detecting and quantifying multiple Sudan dyes in low concentration from illegally adulterated samples.

Dataset Information

Quantification and coupling of the electromagnetic and chemical contributions in surface-enhanced Raman scattering.

Publications

Quantification and coupling of the electromagnetic and chemical contributions in surface-enhanced Raman scattering.

Similar Datasets

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