Surfaces surface enhanced Raman spectra SERS

Replacement of the dinitrogen ligand in [Os(N2)(NH3)5] by pyridine under aerobic conditions or of the weakly bound triflate ligand in [0s(0S02CF3)(NH3)5] + by pyridine yields [Os(py)(NH3)j] cyclic voltammetric studies show reversible reduction to [Os(py)(NH3)5f" 62.90,91 and the surface-enhanced Raman spectrum (SERS) of the complex (both normal and deuteriated) shows Os-N, ammine and internal pyridine vibrational modes. Infrared spectra were also measured. ... 

Well now, the proposed co-reprecipitation method [45] and visible-light-driven photocatalytic reduction method [53] have been established for the purpose of these kinds of core/shell type hybridized NCs composed of PDA NC and noble metal NP, and both processes have been further improved to extend to another type hybridized NCs, respectively [50, 54], Typical core/shell type hybridized NPs were first reported by Halas and Caruso research groups [70, 71, 73, 84, 87]. A great number of fine gold (Au) NPs as Au shell were deposited densely on the surface of silica NPs, which are spherical and uniform size. The LSP speetra were continuously blue-shifted with increasing the thickness of Au shell, and some optoelectronic applications have been now presented such as a substrate for surface enhanced Raman spectrum (SERS) measurement, chemical- and bio-sensors, etc. Silica NPs, however, are core as a template to fabricate core/sheU type hybridized nanostructure, and there is no something like optoelectronic interaction through core/shell hetero nano-interface in this case. 

As for Raman spectroscopy one may expect resonance Raman effect and/or surface-enhanced Raman scattering (SERS). By using these effects, the Raman spectrum of a monolayer film may be enhanced by 103-106. Resonance Raman spectroscopy is useful for exploring the electronic structure of monolayers with a chromophore and SERS technique is applied to study structure, orientation, and interactions of monolayers on a silver or gold surface. 

The molecular cross section of the ordinary Raman effect can be considerably enhanced. If the exciting radiation has a higher frequency, the intensity increases basically by the fourth power of the frequency. Moreover, there is a further increase as electronic absorption bands are approached the pre-resonance and resonance Raman effect (Sections 3.6 and 6.1). Further, the so-called surface-enhanced Raman effect (SERS) increases the molecular cross section. Both effects produce an enhancement of several orders of magnitude (Gerrard, 1991) (see Sec. 6.1). However, these two effects have to be carefully adapted to the specific properties of the investigated molecules. Photochemical decomposition and excitation of fluorescence may make it impossible to record a Raman spectrum. The described techniques may thus be of considerable importance for the solution of special problems, but they are by no means routine techniques to be generally used. 

In the experiments presented here, the fluorophores are adsorbed directly onto the metallic (gold) NP surface. The fluorescence enhancement (if any) is therefore small and the MEF signal may accordingly be weak, especially for weak fluorophores like Rh6G at 633 nm. In fact, the MEF spectrum is accompanied by Raman peaks of comparable intensity (themselves enhanced through Surface Enhanced Raman Scattering, SERS). 

The solvent-induced stereochemical behaviour of a bile acid-based biphenyl phosphite has been studied experimentally using circular dichroism (CD) spectroscopy, and theoretically using DFT quantum mechanical methods. " The FTIR, Raman and surface-enhanced Raman scattering (SERS) spectra of phenyl phosphate disodium salt have been recorded and its vibrational wavenumbers, calculated using the Hartree-Fock/6-31G basis set, compared with experimental values. From SERS spectra study, the molecule is adsorbed on the silver surface with the benzene ring in a tilted orientation. The presence of the phenyl ring and the phosphate group vibrations in the SERS spectrum reveal the interactions between the phenyl... 

Sampling in surface-enhanced Raman and infrared spectroscopy is intimately linked to the optical enhancement induced by arrays and fractals of hot metal particles, primarily of silver and gold. The key to both techniques is preparation of the metal particles either in a suspension or as architectures on the surface of substrates. We will therefore detail the preparation and self-assembly methods used to obtain films, sols, and arrayed architectures coupled with the methods of adsorbing the species of interest on them to obtain optimal enhancement of the Raman and infrared signatures. Surface-enhanced Raman spectroscopy (SERS) has been more widely used and studied because of the relative ease of the sampling process and the ready availability of lasers in the visible range of the optical spectrum. Surface-enhanced infrared spectroscopy (SEIRA) using attenuated total reflection coupled to Fourier transform infrared spectroscopy, on the other hand, is an attractive alternative to SERS but has yet to be widely applied in analytical chemistry. 

Surface-enhanced Raman spectroscopy (S S) has been a focus for much study since it was first reported by Fleischmann and coworkors in 1976 (10). Thus far, a considoable amount of this work has been aimed at undostanding the physical origin of the phenomenon (10-13), but recently there have been many investigations of potential analytical uses for SERS (14-18). Although it has not yet come into general use, SERS is an attractive analytical technique that can detect certain types of molecules with a high level of sensitivity. Furthermore, because SERS is a vibrational spectroscopy, a SER spectrum contains a lot of molecular information. 

Over the past decades, smface enhanced Raman scattering (SERS) has became a valuable spectroscopic technique as a powerful smface diagnostic tool. In 1974 Fleischmann, Hendra, and McQuillan performed the first measurement of a surface Raman spectrum from pyridine adsorbed on an electrochemically roughened silver electrode. It has been explained that some vibrational bands of pyridine are selectively enhanced a million times. This increases the sensitivity of... 

Figure 16 A high-esolution SERS spectrum of peat humic acid that offers information in elucidating metal binding characteristics of humic substances via vibrational assignment of the observed peaks. (Reprinted with permission from YH Yang, HA Chase. Applications of Raman and surface enhanced Raman scattering techniques to humic substances, Spectr Lett 31 821-848, 1998. Copyright 1998 Marcel Dekker, Inc.)...

Surface-enhanced Raman scattering is a surface phenomenon and only molecules close to the substrate surface show enhanced Raman spectra. In a mixture there will be competition for surface sites. If one species is more highly attracted to the surface than another the latter will not show a SERS spectrum. For this reason, we can use SERS spectroscopy for identifying and quantifying the individual adsorb compound in the first monolayer of mixtures of CPC and PNP. The ex situ surface roughening procedure is carried out in a 0.1 M KCl electrolyte solution in the absence of other molecules and the binary mixture of CPC/PNP is then added to the op-toelectrochemical cell. The detailed analysis of the system containing mixtures of CPC and PNP can be summarized as follow ... 

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