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Silver Sol (silver + sol)
Selected AbstractsAdsorption of 3- and 4-benzoylpyridine on colloidal silver particles: a surface-enhanced Raman scattering studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2004Joydeep Chowdhury Abstract Surface-enhanced Raman scattering (SERS) spectra of 3- and 4-benzoylpyridine (BP) adsorbed on silver hydrosols were compared with the FTIR and normal Raman spectra in bulk and in solution. With a small fractional change in adsorbate concentration, the SER spectra of isomeric BPs show significant changes in their features, indicating different orientational changes of the different parts of the flexible molecule on the colloidal silver surface with adsorbate concentration. The appearance of a broad, long-wavelength band in the absorption spectra of the silver sol due to solute-induced coagulation of colloidal silver particles is found to be red shifted with increase in adsorbate concentration. The SER excitation profiles indicate that the resonance of the Raman excitation radiation with the new aggregation band contributes more to the SERS intensity than that with the original sol band. Copyright © 2004 John Wiley & Sons, Ltd. [source] Production of monodisperse silver colloids by reduction with hydrazine: the effect of chloride and aggregation on SER(R)S signal intensity,JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2004U. Nickel Abstract SER(R)S spectra with high signal intensity of Nile Blue A sulfate and 1,1,-diethyl-2,2,-cyanine iodide present in low concentration (,0.05 µM) can be recorded by employing certain silver sols in the absence of any chloride and without highly aggregated particles. The sols have been prepared by reduction of silver nitrate with hydrazine hydrate in a special procedure at a carefully established pH. In the presence of chloride, the maximum SER(R)S signal observed for a ca. 0.5 µM solution of Nile Blue A is of similar magnitude employing either a silver sol according to Lee and Meisel or our sol C, which contains nearly exclusively single silver particles with diameters of about 50 nm. Without added chloride, however, only our sol produces SER(R)S spectra with similar intensity as with chloride. Because the influence of chloride and coagulation on the intensity of the SER(R)S-signal can be controlled by varying the additives to our silver sol, further experiments of this kind can help to elucidate how these two parameters influence the magnitude of the SERS enhancement. Copyright © 2004 John Wiley & Sons, Ltd. [source] Investigations on 1,5-diaminoanthraquinone by laser excitationJOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2003M. Umadevi Abstract Optical absorption and fluorescence emission spectra of 1,5-diaminoanthraquinone (1,5-DAAQ) in different solvents and the surface-enhanced Raman scattering (SERS) spectrum of 1,5-DAAQ in silver sol were investigated. Optical absorption and fluorescence emission studies revealed that the internal and external hydrogen bonds and reorientation of the solvent molecule around the excited state fluorophore are responsible for the observed bathochromic shift and the non-radiative decay process in polar solvents. SERS studies showed that 1,5-DAAQ molecules are chemisorbed through carbonyl groups and the lone pair of electrons on the nitrogen. The orientation of the molecule on the silver surface is found to be stand-on. Copyright © 2002 John Wiley & Sons, Ltd. [source] Nanostructured gold surfaces as reproducible substrates for surface-enhanced Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2007M. Sackmann Abstract Raman spectroscopy is a common tool for the qualitative and quantitative chemical analysis of molecules. Although the unique identification of molecules is possible via their vibrational lines, high concentrations (mmol/l) are needed for their nonresonant excitation owing to their low scattering cross section. The intensity of the Raman spectra is amplified by the use of the surface-enhanced Raman scattering (SERS) technique. While the use of silver sols results only in a limited reproducibility of the Raman line intensities, lithographically designed, nanostructured gold surfaces used as SERS-active substrates should, in principle, combine the high sensitivity with better reproducibility. For this purpose, we have produced gratings of gold dots on Si(001) surfaces by means of electron beam lithography. Qualitative and quantitative investigations of crystal violet (CV) performed using nanostructured surfaces give high reproducibility and enhancement of the Raman lines. The substrates are reusable after cleaning; all results presented could be obtained from a single SERS substrate. For the experiments very low laser powers were used. Copyright © 2006 John Wiley & Sons, Ltd. [source] Production of monodisperse silver colloids by reduction with hydrazine: the effect of chloride and aggregation on SER(R)S signal intensity,JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2004U. Nickel Abstract SER(R)S spectra with high signal intensity of Nile Blue A sulfate and 1,1,-diethyl-2,2,-cyanine iodide present in low concentration (,0.05 µM) can be recorded by employing certain silver sols in the absence of any chloride and without highly aggregated particles. The sols have been prepared by reduction of silver nitrate with hydrazine hydrate in a special procedure at a carefully established pH. In the presence of chloride, the maximum SER(R)S signal observed for a ca. 0.5 µM solution of Nile Blue A is of similar magnitude employing either a silver sol according to Lee and Meisel or our sol C, which contains nearly exclusively single silver particles with diameters of about 50 nm. Without added chloride, however, only our sol produces SER(R)S spectra with similar intensity as with chloride. Because the influence of chloride and coagulation on the intensity of the SER(R)S-signal can be controlled by varying the additives to our silver sol, further experiments of this kind can help to elucidate how these two parameters influence the magnitude of the SERS enhancement. Copyright © 2004 John Wiley & Sons, Ltd. [source] Study of interaction between aspartic acid and silver by surface-enhanced Raman scattering on H2O and D2O solsBIOPOLYMERS, Issue 5 2001J. F. Arenas Abstract Three different surface-enhanced Raman scattering (SERS) spectra are recorded for aspartic acid on H2O silver sols under different concentrations and pH values. The analysis of the results shows that it interacts with the metal surface in its dianionic form in two different ways, depending on the pH and concentration. Moreover, in some cases the fumarate anion is detected, which results from the chemical surface transformation of the aspartate. The N -deuterated aspartic acid adsorbed on the D2O silver sols gives rise to only one SERS spectrum as a consequence of the interaction of amino and carboxylate functional groups of the dianion with the metal, independent of the concentration and pD. © 2001 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 241,248, 2001 [source] | ||||||||||