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SERS Activity (ser + activity)
Selected AbstractsTowards a quantitative SERS approach , online monitoring of analytes in a microfluidic system with isotope-edited internal standardsJOURNAL OF BIOPHOTONICS, Issue 4 2009Anne März Abstract In this contribution a new approach for quantitative measurements using surface-enhanced Raman spectroscopy (SERS) is presented. Combining the application of isotope-edited internal standard with the advantages of the liquid,liquid segmented-flow-based approach for flow-through SERS detection seems to be a promising means for quantitative SERS analysis. For the investigations discussed here a newly designed flow cell, tested for ideal mixing efficiency on the basis of grayscale-value measurements, is implemented. Measurements with the heteroaromatics nicotine and pyridine using their respective deuterated isotopomers as internal standards show that the integration of an isotopically labeled internal standard in the used liquid,liquid two-phase segmented flow leads to reproducible and comparable SERS spectra independent from the used colloid. With the implementation of an internal standard into the microfluidic device the influence of the properties of the colloid on the SERS activity can be compensated. Thus, the problem of a poor batch-to-batch reproducibility of the needed nanoparticle solutions is solved. To the best of our knowledge these are the first measurements combining the above mentioned concepts in order to correct for differences in the enhancement behaviour of the respective colloid. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Adjustment and control of SERS activity of metal substrates by pressureJOURNAL OF RAMAN SPECTROSCOPY, Issue 4 2010Lixin Xia Abstract Metal pellets of silver and copper for surface-enhanced Raman scattering (SERS) spectroscopy were prepared by compression with different pressures. It was found that the SERS activity of the pellet could be controlled by pressure. Enhanced Raman scattering properties of the metal pellets in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA) with excitation at 632.8 or 514 nm could be obtained by choosing proper pressure of pellatization. The SERS peak intensity of the band at ,1584 cm,1 of 4-MBA adsorbed on the metal pellets varies as a function of applied pressure, and which is about 1.2,32 times greater than when it is adsorbed on silver and copper particles. The calculated results of three-dimensional finite-difference time-domain method (3D-FDTD) are in good agreement with the experimental data. Moreover, no spurious peaks appear in the SERS spectra of the samples because no other chemicals are involved in the simple preparation process of the metal pellets, which will facilitate its use as an SERS-active substrate for analytical purposes. In summary, SERS-active metal pellets can be produced simply and cost effectively by the method reported here, and this method is expected to be utilized in the development of SERS-based analytical devices. Copyright © 2009 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman scattering spectroscopy via gold nanostarsJOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2009E. Nalbant Esenturk Abstract Anisotropic metallic nanoparticles (NPs) have unique optical properties, which lend them to applications such as surface-enhanced Raman scattering (SERS) spectroscopy. Star-shaped gold (Au) NPs were prepared in aqueous solutions by the seed-mediated growth method and tested for Raman enhancement using 2-mercaptopyridine (2-MPy) and crystal violet (CV) probing molecules. For both molecules, the SERS activity of the nanostars was notably stronger than that of the spherical Au NPs of similar size. The Raman enhancement factors (EFs) for 2-MPy on Au nanostars and nanorods are comparable and estimated as greater than 5 orders of magnitude. However, the enhancement for CV on nanostars was significantly higher than for nanorods, in particular at CV concentrations of 100 nM or lower. This article is a US Government work and is in the public domain in the USA. Published in 2008 by John Wiley & Sons, Ltd. [source] Aggregation and surface-enhanced Raman activity study of dye-coated mixed silver,gold colloidsJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2004Jinghuai Fang Abstract The aggregate morphologies of silver, gold, and mixed silver,gold nanoparticles coated with fuchsine basic were directly investigated by means of transmission electron microscopy. It was found that the aggregation of silver and gold colloids induced by the adsorption of fuchsine basic displayed different aggregate characteristics. The adsorption of fuchsine basic in mixed silver and gold colloidal systems led to altered aggregation and surface-enhanced Raman scattering (SERS) enhancement behavior. A suitable ratio of mixed silver and gold colloids could form a favorable state of aggregation and significantly increase the SERS activity of mixed colloids compared with single silver and gold colloids. This is the first report of the SERS of fuchsine basic on mixed silver and gold colloids. Copyright © 2004 John Wiley & Sons, Ltd. [source] Silver Coated Platinum Core,Shell Nanostructures on Etched Si Nanowires: Atomic Layer Deposition (ALD) Processing and Application in SERSCHEMPHYSCHEM, Issue 9 2010Vladimir A. Sivakov Dr. Abstract A new method to prepare plasmonically active noble metal nanostructures on large surface area silicon nanowires (SiNWs) mediated by atomic layer deposition (ALD) technology has successfully been demonstrated for applications of surface-enhanced Raman spectroscopy (SERS)-based sensing. As host material for the plasmonically active nanostructures we use dense single-crystalline SiNWs with diameters of less than 100 nm as obtained by a wet chemical etching method based on silver nitrate and hydrofluoric acid solutions. The SERS active metal nanoparticles/islands are made from silver (Ag) shells as deposited by autometallography on the core nanoislands made from platinum (Pt) that can easily be deposited by ALD in the form of nanoislands covering the SiNW surfaces in a controlled way. The density of the plasmonically inactive Pt islands as well as the thickness of noble metal Ag shell are two key factors determining the magnitude of the SERS signal enhancement and sensitivity of detection. The optimized Ag coated Pt islands on SiNWs exhibit great potential for ultrasensitive molecular sensing in terms of high SERS signal enhancement ability, good stability and reproducibility. The plasmonic activity of the core-shell Pt//Ag system that will be experimentally realized in this paper as an example was demonstrated in numerical finite element simulations as well as experimentally in Raman measurements of SERS activity of a highly diluted model dye molecule. The morphology and structure of the core-shell Pt//Ag nanoparticles on SiNW surfaces were investigated by scanning- and transmission electron microscopy. Optimized core,shell nanoparticle geometries for maximum Raman signal enhancement is discussed essentially based on the finite element modeling. [source] | ||||||||||