SERRS resonance

Surface-enhanced resonance Raman scattering (SERRS), 21 327-328 advantage of, 21 329 Surface Evolver software, 12 11 Surface excess, 24 135, 136 Surface extended X-ray absorption fine structure (SEXAFS), 19 179 24 72 Surface filtration, 11 322-323 Surface finish(es). See also Electroplating in electrochemical machining, 9 591 fatigue performance and, 13 486-487 Surface finishing agents, 12 33 Surface force apparatus, 1 517 Surface force-pore flow (SFPF) model,... 

Although chemisorption is not essential, when it does occur there may be further enhancement of the Raman signal, since the formation of new chemical bonds and the consequent perturbation of adsorbate electronic energy levels can lead to a surface-induced RR effect. The combination of surface and resonance enhancement (SERRS) can occur when adsorbates have intense electronic absorption bands in the same spectral region as the metal surface plasmon resonance, yielding an overall enhancement as large as 10lo-1012. 

The use of surface-enhanced resonance Raman spectroscopy (SERRS) as an identification tool in TLC and HPLC has been investigated in detail. The chemical structures and common names of anionic dyes employed as model compounds are depicted in Fig. 3.88. RP-HPLC separations were performed in an ODS column (100 X 3 mm i.d. particla size 5 pm). The flow rate was 0.7 ml/min and dyes were detected at 500 nm. A heated nitrogen flow (200°C, 3 bar) was employed for spraying the effluent and for evaporating the solvent. Silica and alumina TLC plates were applied as deposition substrates they were moved at a speed of 2 mm/min. Solvents A and B were ammonium acetate-acetic acid buffer (pH = 4.7) containing 25 mM tributylammonium nitrate (TBAN03) and methanol, respectively. The baseline separation of anionic dyes is illustrated in Fig. 3.89. It was established that the limits of identification of the deposited dyes were 10 - 20 ng corresponding to the injected concentrations of 5 - 10 /ig/ml. It was further stated that the combined HPLC-(TLC)-SERRS technique makes possible the safe identification of anionic dyes [150],... 

R.M. Seifar, M.A.F. Altelaar, RJ. Dijkstra, F. Ariese, U.A. Th. Brinkman and C. Gooijer, Surface-enhanced resonance Raman spectroscopy (SERRS) as an identification tool in column liquid chromatography. Anal. Chem., 72 (2000) 5718-5724. 

SERRS surface enhanced resonance Raman TEA target factor analysis... 

Another method for assaying the activity and stereoselectivity of enzymes at in vitro concentrations is based on surface-enhanced resonance Raman scattering (SERRS) using silver nanoparticles (116). Turnover of a substrate leads to the release of a surface targeting dye, which is detected by SERRS. In a model study, lipase-catalyzed kinetic resolution of a dye-labeled chiral ester was investigated. It is currently unclear how precise the method is when identifying mutants which lead to E values higher than 10. The assay appears to be well suited as a pre-test for activity. 

Li et al. have performed a comparative study on the surface-enhanced resonance hyper-Raman scattering and surface-enhanced resonance Raman scattering (SERRS) of dyes adsorbed on Ag electrode and Ag colloid [210]. 

Electrochemical, SERS, and surface enhanced resonance Raman (SERR) studies of the reduction of methylene blue on silver electrode have been published by Nicolai et al. [230, 231]... 

S S CONTENTS Preface, C. Allen Bush. Methods in Macromo-lecular Crystallography, Andrew J. Howard and Thomas L. Poulos. Circular Dichroism and Conformation of Unordered Polypeptides, Robert W. Woody. Luminescence Studies with Horse Liver Dehydrogenase Information on the Structure, Dynamics, Transitions and Interactions of this Enzyme, Maurice R. Eftink. Surface-Enhanced Resonance Raman Scattering (SERRS) Spectroscopy A Probe of Biomolecular Structure and Bonding at Surfaces, Therese M. Cotton, Jae-Ho Kim and Randall E. Holt. Three-Dimensional Conformations of Complex Carbohydrates, C. Allen Bush and Perse-veranda Cagas. Index. 

Surface-enhanced resonance Raman scattering (SERRS) has also been achieved using silver colloid aggregates produced in situ in the chip. This method was used to detect an azo dye, 5-(2,-methyl-3,5,-dinitrophenylazo)quinolin-8-ol, which is a derivative of the explosive, TNT. With this method, it was possible to detect 10 iL of 10 9 M dye (or 10 fmol). This represented a 20-fold increase in sensitivity over that achieved using a macro flow cell [739]. 

Since stationary electrodes are employed in most SERS experiments, a relatively small number of adsorbed molecules are continuously irradiated by laser beams. When exciting lines are within strong absorption bands of the adsorbed species, surface-enhancement resonance Raman spectra (SERRS) are obtained. However, this may lead to decomposition of such species due to local heating. Use of a cylindrical rotating electrode can circumvent this problem (57). 

Trace amounts of the nitrite ion (NO ) are indicative of the extent of pollution and eutrophication. The multitude of methods that can measure nitrite ion concentrations, such as colorimetry, chemiluminescence or fluorimetry, are not capable of detecting subnanomole amounts of nitrite. These also suffer from interference problems. A highly sensitive and selective method for the determination of low concentrations of nitrite in aqueous solutions using surface-enhanced resonance Raman (SERRS) has been developed (13) (see Section 3.3). 

Further enhancement can be observed if the exciting light additionally couples into an electronic transition of the adsorbate (surface-enhanced resonance Raman scattering, SERRS). In this case, enhancement factors of... 

Certain roughened surfaces (Ag or Au colloids) exhibit another nice intensification of the Raman effect of 103 to 106 by exciting surface plasmons in the colloid particles this is surface-enhanced Raman, first seen by Fleischmann54, and explained by van Duyne.55 Combining resonance and surface-enhanced effects in surface-enhanced resonance Raman spectroscopy (SERRS), the Raman intensity can increase by factors as large as 1012, so that solutions of concentration down to 10 12 M can be detected. 

The classical Raman effect produces only very weak signals. There are two techniques which very successfully enhance this effect. The resonance Raman spectroscopy RRS is making use of the excitation of molecules in a spectral range of electronic absorption. The surface-enhanced Raman spectroscopy SERS employs the influence of small metal particles on the elementary process of Raman scattering. These two techniques may even be combined surface-enhanced resonance Raman effect SERRS. Such spectra are recorded with the same spectrometers as classical Raman spectra, although different conditions of the excitation and special sample techniques are used (Sec. 6.1). 

Since the pioneering work by Cotton et al. on heme proteins (Cotton et al., 1980), surface enhanced resonance Raman spectroscopy (SERRS), Sec. 6.1, has been used to study a large variety of biomolecules, such as retinal proteins (Nabiev et al., 1985), flavoproteins (Coperland et al., 1984 Holt and Cotton, 1987), chlorophylls (Cotton and Van Duyne, 1982 Hildebrandt and Spiro, 1988), and oxyhemoglobins (de Groot and Hesters, 1987). The advantages of this technique include low sample concentration and fluorescence quenching. The main question is whether or not the native structure and function of the molecule is preserved on the metal surface. 

Figure 3.2 SEF at 514.S nm are illustrated using Langmuir-Blodgett monolayer of a PTCD derivative on silver islands with a plasmon resonance in resonance with the molecular absorption. After quenching the Fluorescence with Ag overlayers LB-SERRS, with its overtone series, is clearly seen. The pre-resonant SERS excited at 632.8 nm is also shown to highlight the differences in the intensities of fundamental and overtones bands compared to SERRS.

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