Investigation of Mass-Produced Substrates for Reproducible Surface-Enhanced Raman Scattering Measurements over Large Areas (original) (raw)
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Surface enhanced Raman scattering (SERS)—a quantitative analytical tool?
Journal of Raman Spectroscopy, 2006
Raman spectroscopy is a widely used analytical tool capable of providing valuable information about the chemical structure and composition of molecules. In order to detect substances also at a very low concentration levels, Surface Enhanced Raman Scattering (SERS) was introduced. The different amplification mechanisms result in extreme sensitivity, however, a quantitative use of SERS appears to be problematic. Especially, when deploying silver sols as SERS substrates, the reproducibility of the signal intensities for a given substance concentration is questionable. Experimental results of an investigation of this problem for low concentrations of adenine are presented. Comparison with results obtained for different SERS substrates by other authors reveals clearly different dependencies. Only in a very limited concentration range reproducible and therefore quantitatively utilizable data could be obtained.
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Surface-enhanced Raman scattering (SERS) has become a powerful tool in chemical, material and life sciences, owing to its intrinsic features (i.e., fingerprint recognition capabilities and high sensitivity) and to the technological advancements that have lowered the cost of the instruments and improved their sensitivity and user-friendliness. We provide an overview of the most significant aspects of SERS. First, the phenomena at the basis of the SERS amplification are described. Then, the measurement of the enhancement and the key factors that determine it (the materials, the hot spots, and the analyte-surface distance) are discussed. A section is dedicated to the analysis of the relevant factors for the choice of the excitation wavelength in a SERS experiment. Several types of substrates and fabrication methods are illustrated, along with some examples of the coupling of SERS with separation and capturing techniques. Finally, a representative selection of applications in the biomed...
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This thesis presents a rigorous stepwise methodology towards the accurate measurement and quantification of the SERS enhancement factor (EF), the key parameter in describing the SERS effect. The work represents, we believe, a successful attempt to resolve some of the inconsistencies in the literature and to refocus the field by emphasizing the importance of consistent definitions and rigorous quantification to elucidate matters of fundamental importance in SERS. The success in our approach is that it combines careful experimental measurements upon a sound theoretical framework, and utilizes a 'toolbox' of techniques developed in recent years, such as bi-analyte SERS (BiASERS) techniques for single-molecule (SM) detection, and isotopic editing. In experimental work, we measure the bare Raman cross-sections of five common probes used in SERS as a first step in measuring the analytical enhancement factor (AEF) and single-molecule enhancement factor (SMEF). The methodology in me...
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Following the recognition of the surface-enhanced Raman scattering effect in 1977, there was an explosion of research aimed at understanding this phenomenon of molecular interactions with nano-scale particles, and more than 1000 papers were published by 1982. Since the mid-1990's there has been a resurgence in SERS-based research with the detection of single-molecules and the acknowledgement of ``hot-spots''. These measurements provoked new examination of SERS theory with a focus on the structure of these hot spots: fractal clusters, edges, or inter-particle gaps. Meanwhile, Real-Time Analyzers has been developing SERS-active sample systems and analyzers to exploit this phenomenon for trace chemical analysis. This presentation reviews the analytical capabilities and limitations for many of the SERS-active substrates, as well as RTA's metal-doped sol-gels. The latter includes the use of the sol-gels in sample systems and analyzers, and their application to poisons in water supplies, food contamination, drug and explosives detection and proteomics.
The Analyst, 2015
This paper demonstrates a renewed procedure for the quantification of surface-enhanced Raman scattering (SERS) enhancement factors with improved precision. The principle of this method relies on deducting the resonance Raman scattering (RRS) contribution from surface-enhanced resonance Raman scattering (SERRS) to end up with the surface enhancement (SERS) effect alone. We employed 1,8,15,22-tetraaminophthalocyanato-cobalt(II) (4α-Co(II)TAPc), a resonance Raman- and electrochemically redox-active chromophore, as a probe molecule for RRS and SERRS experiments. The number of 4α-Co(II)TAPc molecules contributing to RRS and SERRS phenomena on plasmon inactive glassy carbon (GC) and plasmon active GC/Au surfaces, respectively, has been precisely estimated by cyclic voltammetry experiments. Furthermore, the SERS substrate enhancement factor (SSEF) quantified by our approach is compared with the traditionally employed methods. We also demonstrate that the present approach of SSEF quantifica...
Surface and Interface Analysis, 2008
Surface-enhanced Raman scattering (SERS) is a powerful technique of Raman signal detection of substances at a low concentration level. It allows observation of structural details of films with very small thicknesses. It is possible to achieve the enhancement of Raman signal of species located on the surface of properly prepared SERS-active substrates of up to ca 10 6 . One of the main requirements for the substrate to be SERS-active is the proper roughness of the surface. In this work different SERS-active Au and Ag substrates suitable for spectral mapping were prepared using procedures which consisted of electrochemical deposition of metal layer and further roughening with oxidation-reduction cycles (ORC) treatment. The nanostructures of the metal surfaces were tested using atomic force microscopy (AFM). Monolayers formed both by covalent and noncovalent linkages to the metal surface were detected and Raman spectral maps were then measured. Roughening procedure of the substrates was optimized and its effect on the SERS enhancement was discussed. The relations among the surface nanostructure, optimal roughening, type of linkage of the analyte to the surface of the substrate and the Raman signal enhancement for the experimental conditions were studied.
Synthesis of large flower-like substrates for surface-enhanced Raman scattering
Chemical Engineering Journal, 2014
h i g h l i g h t s A new, well-designed type of large flower-like SERS substrate is synthesized. The new substrates exhibit high and reproducible SERS enhancement. The new substrates are expected to be applied in SERS-based analytical devices. g r a p h i c a l a b s t r a c t A new, well-designed type of large flower-like SERS substrate is synthesized by treating 3 Å molecular sieves with dilute hydrofluoric acid to prepare a support and then plating silver nanoparticles on this support.