Towards Reliable and Quantitative Surface‐Enhanced Raman Scattering (SERS): From Key Parameters to Good Analytical Practice

Experimental results obtained in different laboratories world‐wide by researchers using surface‐enhanced Raman scattering (SERS) can differ significantly. We, an international team of scientists with long‐standing expertise in SERS, address this issue from our perspective by presenting considerations on reliable and quantitative SERS. The central idea of this joint effort is to highlight key parameters and pitfalls that are often encountered in the literature. To that end, we provide here a series of recommendations on: a) the characterization of solid and colloidal SERS substrates by correlative electron and optical microscopy and spectroscopy, b) on the determination of the SERS enhancement factor (EF), including suitable Raman reporter/probe molecules, and finally on c) good analytical practice. We hope that both newcomers and specialists will benefit from these recommendations to increase the inter‐laboratory comparability of experimental SERS results and further establish SERS as an analytical tool.Peer Reviewe

Raman spectroscopic techniques for meat analysis: A review

Raman spectroscopy (vibrational spectroscopy) proved to be an effective analytical approach in the field of geology, semiconductors, materials and polymers. Over the past decade, Raman spectroscopy has attracted the attention of researchers as a non-destructive, highly sensitive, fast and eco-friendly method and has demonstrated the unique capabilities of food analysis. The use of Raman spectroscopic methods (RSMs) to assess the quality of meat and finished products is rapidly expanding. From the analysis of one sample, you can get a large amount of information about the structure of proteins, the composition of fatty acids, organoleptic parameters, autolysis and spoilage indicators, authentication of raw materials, technological properties. An important advantage of the method is the comparability of the results obtained with the data of traditional analytical methods. Traditional methods of determining the quality of meat are often time-consuming, expensive and lead to irreversible damage to a sample. It is difficult to use them in production conditions directly on the meat processing lines. Technological advances have made it possible to develop portable Raman spectroscopes to use directly in production. The article presents the basic principles of Raman spectroscopy, system  atizes the results of the use of RSMs for the analysis of meat quality from different types of slaughter animals and provides tools for analyzing the data of the obtained spectra. Raman spectra have many dependent variables, so chemometric assays are used to work with them. Literature analysis has shown that currently there is no unified database of meat spectra in the world, standardized protocols for conducting research and processing the obtained results. In Russia, the use of RSMs is a new,Raman spectroscopy (vibrational spectroscopy) proved to be an effective analytical approach in the field of geology, semiconductors, materials and polymers. Over the past decade, Raman spectroscopy has attracted the attention of researchers as a non-destructive, highly sensitive, fast and eco-friendly method and has demonstrated the unique capabilities of food analysis. The use of Raman spectroscopic methods (RSMs) to assess the quality of meat and finished products is rapidly expanding. From the analysis of one sample, you can get a large amount of information about the structure of proteins, the composition of fatty acids, organoleptic parameters, autolysis and spoilage indicators, authentication of raw materials, technological properties. An important advantage of the method is the comparability of the results obtained with the data of traditional analytical methods. Traditional methods of determining the quality of meat are often time-consuming, expensive and lead to irreversible damage to a sample. It is difficult to use them in production conditions directly on the meat processing lines. Technological advances have made it possible to develop portable Raman spectroscopes to use directly in production. The article presents the basic principles of Raman spectroscopy, system  atizes the results of the use of RSMs for the analysis of meat quality from different types of slaughter animals and provides tools for analyzing the data of the obtained spectra. Raman spectra have many dependent variables, so chemometric assays are used to work with them. Literature analysis has shown that currently there is no unified database of meat spectra in the world, standardized protocols for conducting research and processing the obtained results. In Russia, the use of RSMs is a new, promising and relevant area of research in the field of meat quality

Application of Plasmon Resonances to Surface Enhanced Raman Scattering (SERS), Heat-Assisted Magnetic Recording (HAMR), and All-Optical Magnetic Recording

In this work, we perform the analytical and numerical analyses of the plasmon modes in different metallic nanostructures for the applications to surface-enhanced Raman scattering (SERS), heat-assisted magnetic recording (HAMR) and all-optical magnetic recording. We start with the introduction of physical origin of plasmon resonances in nanoparticles and the eigenmode analysis technique adopted throughout this work in Chap. 1. The excitation of the plasmon modes in nanoparticles subject to optical radiation is also presented. In Chap. 2, we study the dispersion in the SERS enhancement factors with silver nanocube dimers. We perform the mode analysis and calculated the resonance wavelengths of the dipolar plasmon modes in silver nanocube dimers with different configurations. The results show that the SERS enhancement factors are related to the resonance frequencies of the dimers, which are determined by their gap distances and orientations. In Chap. 3, we analytically derive the formula for the computation of resonance permittivities of plasmon modes in spheroidal nanoshells. The dipolar plasmon modes in spheroidal nanoshells possess rotational symmetry which preserves the helicity of circularly polarized light, and consequently, they are useful in all-optical magnetic recording. We have also derived the formulas which indicate how the dipolar plasmon modes in ellipsoidal nanoshells can be excited by uniformly incident field. Light intensities of the optical spots generated by the circularly polarized plasmon modes in spherical nanoshells are computed and compared with those generated by circularly polarized plasmon modes in spheroidal nanoshells. In Chap. 4, we study the plasmon resonances in T-shaped aperture metallic nanofilms and lollipop metallic nanodisks placed nearby different dielectric substrates used in heat-assisted magnetic recording. We developed a constrained eigenvalue problem for specific coupled boundary integral equations to take into account the effect of the surrounding finite dielectric objects. By solving this problem, the resonance frequencies of such metallic nanostructures as well as the corresponding plasmon modes can be computed. The effect of heat sink layers on the plasmon resonances is also discussed. Finally, in Chap. 5, we study the radiation corrections of plasmon resonances in nanoparticles. The red-shifts in resonance frequencies of dipolar plasmon modes with nanocube size are computed and compared with experimental measurement. The results suggest that different dipolar modes have different sensitivities to the rounding of the cube corners and edges

Raman spectroscopic techniques for meat analysis: A review

Raman spectroscopy (vibrational spectroscopy) proved to be an effective analytical approach in the field of geology, semiconductors, materials and polymers. Over the past decade, Raman spectroscopy has attracted the attention of researchers as a non-destructive, highly sensitive, fast and eco-friendly method and has demonstrated the unique capabilities of food analysis. The use of Raman spectroscopic methods (RSMs) to assess the quality of meat and finished products is rapidly expanding. From the analysis of one sample, you can get a large amount of information about the structure of proteins, the composition of fatty acids, organoleptic parameters, autolysis and spoilage indicators, authentication of raw materials, technological properties. An important advantage of the method is the comparability of the results obtained with the data of traditional analytical methods. Traditional methods of determining the quality of meat are often time-consuming, expensive and lead to irreversible damage to a sample. It is difficult to use them in production conditions directly on the meat processing lines. Technological advances have made it possible to develop portable Raman spectroscopes to use directly in production. The article presents the basic principles of Raman spectroscopy, system  atizes the results of the use of RSMs for the analysis of meat quality from different types of slaughter animals and provides tools for analyzing the data of the obtained spectra. Raman spectra have many dependent variables, so chemometric assays are used to work with them. Literature analysis has shown that currently there is no unified database of meat spectra in the world, standardized protocols for conducting research and processing the obtained results. In Russia, the use of RSMs is a new

Dielektrične metapovršine za površinsko ojačeno Ramanovo spektroskopijo

I present the use of high refractive index dimers for the realisation of a surface enhanced Raman spectroscopy substrate. The use of low loss dielectric materials is favourable to metallic ones because of their lower light absorption and consequently much lower heating of the substrate. By combining different mechanisms of field enhancement we can overcome the main weakness of dielectric dimers: a low enhancement factor compared to the plasmonic ones. Results of finite element method simulations for two designed structures are presented. The first structure employs a gold mirror for additional field enhancement, while the second one is adapted for easier fabrication. The enhancement factors and absorption of both structures are compared to the plasmonic and other dielectric substrates.V tem magistrskem delu predstavim uporabo parov delcev z visokim lomnim količnikom za izdelavo površine za površinsko ojačano Ramanovo spektroskopijo. Uporaba dielektričnih materialov z nizkimi izgubami je v primerjavi s kovinskim materialom primernejša, zaradi manjše absorpcije in posledično manjšega segrevanja površine. S kombinacijo različnih ojačevalnih mehanizmov polja lahko premagamo glavno šibkost dielektričnih parov delcev: to je nizek ojačitveni faktor v primerjavi s plazmonskimi sipalci. Predstavljeni so rezultati simulacij z metodo končnih elementov za dve oblikovani strukturi. Pri prvi uporabimo zlato zrcalo za dodatno ojačenje polja, med tem ko je druga prilagojena za lažjo izdelavo. Ojačitveni faktorji in absorpcija obeh struktur so primerjani s plazmonskimi in dielektričnimi strukturami