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Surface-enhanced Raman Scattering (Surface-enhance + raman_scattering)
Selected AbstractsHighly Surface-roughened "Flower-like" Silver Nanoparticles for Extremely Sensitive Substrates of Surface-enhanced Raman ScatteringADVANCED MATERIALS, Issue 45 2009Hongyan Liang Abstract Surface-enhanced Raman scattering (SERS) is a new optical spectroscopic analysis technique with potential for highly sensitive detection of molecules. Recently, many efforts have been made to find SERS substrates with high sensitivity and reproducibility. In this Research News article, we provide a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, "flower-like" morphology by reducing silver nitrate with ascorbic acid in aqueous solutions. The nanometer-scale surface roughness of the particles can provide several hot spots on a single particle, which significantly increases SERS enhancement. The incident polarization-dependent SERS of individual particles is also studied. Although the different "hot spots" on a single particle can have a strong polarization dependency, the total Raman signals from an individual particle usually have no obvious polarization dependency. Moreover, these flower-like silver particles can be measured by SERS with high enhancement several times, which indicates the high stability of the hot spots. Hence, the flower-like silver particles here can serve as highly sensitive and reproducible SERS substrates. [source] Nanoaggregate-Embedded Beads as Novel Raman Labels for BiodetectionADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Ping-Ji Huang Abstract Novel Raman tags called nanoaggregate-embedded beads (NAEBs) have been developed. NAEBs are silica-coated, dye-induced aggregates of a small number of metal nanoparticles. In this work, the Raman reporters used to induce aggregation of gold nanoparticles include strongly binding dyes such as XRITC, TRITC, and DTDC and weakly binding dyes such as R6G. Surface-enhanced Raman scattering (SERS) signal from a single NAEB can be detected. This study also demonstrates that these SERS-active beads can be used as Raman tags for bio-detection. [source] Highly Surface-roughened "Flower-like" Silver Nanoparticles for Extremely Sensitive Substrates of Surface-enhanced Raman ScatteringADVANCED MATERIALS, Issue 45 2009Hongyan Liang Abstract Surface-enhanced Raman scattering (SERS) is a new optical spectroscopic analysis technique with potential for highly sensitive detection of molecules. Recently, many efforts have been made to find SERS substrates with high sensitivity and reproducibility. In this Research News article, we provide a focused review on the synthesis of monodispersed silver particles with a novel, highly roughened, "flower-like" morphology by reducing silver nitrate with ascorbic acid in aqueous solutions. The nanometer-scale surface roughness of the particles can provide several hot spots on a single particle, which significantly increases SERS enhancement. The incident polarization-dependent SERS of individual particles is also studied. Although the different "hot spots" on a single particle can have a strong polarization dependency, the total Raman signals from an individual particle usually have no obvious polarization dependency. Moreover, these flower-like silver particles can be measured by SERS with high enhancement several times, which indicates the high stability of the hot spots. Hence, the flower-like silver particles here can serve as highly sensitive and reproducible SERS substrates. [source] Surface-enhanced Raman scattering and density functional theory studies of bis(4-aminophenyl)sulfone,JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2010Guillermo Diaz-Fleming Abstract Raman and surface-enhanced Raman scattering (SERS) spectra of dapsone by using colloidal silver nanoparticles have been recorded. Density functional theory was used for the optimization of ground state geometries and simulation of the vibrational spectrum of this molecule. The SERS spectrum with a large silver cluster as a model metallic surface was simulated for the first time. Taking into account the experimental and calculated Raman as well as the SERS normal modes and the corresponding assignments, along with the modeling of the free dapsone and the one in the presence of the colloidal silver nanoparticles, the importance of the sulfone group on the SERS effect in dapsone was inferred. Copyright © 2009 John Wiley & Sons, Ltd. [source] Size-dependent SERS enhancement of colloidal silver nanoplates: the case of 2-amino-5-nitropyridineJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2009A. C. Sant'Ana Abstract Surface-enhanced Raman scattering (SERS) spectra of 2-amino-5-nitropyridine (ANP) adsorbed on colloidal silver triangular nanoplates were obtained using samples with different mean sizes and surface plasmon frequencies. The relative SERS enhancement factor for each sample was determined by the analysis of the normalized SERS excitation profiles of ANP vibrational modes for nanoplates in suspension, without aggregation. The SERS profiles are blue-shifted in relation to the localized surface plasmon peak. The detailed characterization of both morphology and concentration of the samples in addition to a rigorous normalization of the SERS spectra allowed a quantitative correlation between the SERS profiles and the mean size of the nanoplates. This correlation indicated the existence of an optimum size of the nanoplates for maximum Raman enhancement. Copyright © 2008 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman scattering from gold-coated germanium oxide nanowiresJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2008Muhammad A. Khan Abstract We utilized bulk-synthesized nanowires (NWs) of germanium dioxide as nanoscale structures that can be coated with noble metals to allow the excitation of surface plasmons over a broad frequency range. The NWs were synthesized on substrates of silicon using gold-catalyst-assisted vapor,liquid,solid (VLS) growth mechanism in a simple quartz tube furnace setup. The resulting NWs have diameters of ,100,200 nm, with lengths averaging ,10,40 µm and randomly distributed on the substrate. The NWs are subsequently coated with thin films of gold, which provide a surface-plasmon-active surface. Surface-enhanced Raman scattering (SERS) studies with near-infrared (NIR) excitation at 785 nm show significant enhancement (average enhancement > 106) with good uniformity to detect submonolayer concentrations of 4-methylbenzenethiol (4-MBT), trans -1,2-bis(4-pyridyl)ethylene (BPE), and 1,2-benzendithiol (1,2-BDT) probe molecules. We also observed an intense, broad continuum in the Raman spectrum of NWs after metal coating, which tended to diminish with the analyte monolayer formation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Some aspects of SERS temporal fluctuations: analysis of the most intense spectra of hydrogenated amorphous carbon deposited on silverJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2007Andrzej Kudelski Abstract Surface-enhanced Raman scattering (SERS) spectra of hydrogenated amorphous carbon (aC:H) deposited on silver substrates have been recorded with a confocal Raman microscope. When scattered radiation is collected during a short time from an area of a few square micrometres, the subsequently measured SERS spectra often exhibit strong temporal changes (fluctuations). In this paper we present examples of spectra for which the intensity maxima of the fluctuating narrow Raman bands are significantly higher than that of the background (the background is usually dominated by two broad Raman bands centred at about 1350 and 1590 cm,1). In a series of successively measured spectra, one can find spectra with noticeably different total integral intensity. This suggests that the results of averaging the spectra revealing strong and weak fluctuations may be different (at least in intensity). The influence of some electrolytes on the SERS spectral fluctuations is also analysed. Our experiments revealed that the efficiencies of quenching of the SERS spectral fluctuations by various electrolytes are significantly different. We suggest that only anions directly interacting with the metal surface quench strong SERS fluctuations, and that the large differences between chloride and perchloride solutions are caused by differences in the strength of interaction of Cl, and ClO4, anions with the silver surface. Copyright © 2007 John Wiley & Sons, Ltd. [source] Chemical modification and surface reactions on carbon fibers studied by SERSJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2006Bing Xu Abstract Carbon fibers were modified by reacting with maleic anhydride (MA) and oxidation in nitric acid to alter their inert nature. Bismaleimide, acting as a model compound of polyimide, was chosen to react with the surface-active carbon fibers. Surface-enhanced Raman scattering was performed by chemically depositing Ag colloids on different carbon fiber samples, including raw, modified and post-reaction materials. The obtained enhanced Raman spectra explained the surface chemistry of the different carbon fiber samples and their further interaction with bismaleimide. The results could serve as a guide for the design of functional groups on carbon fibers and the manufacture of the carbon-fiber-reinforced polyimide matrix composites. Moreover, the effect of different laser powers and laser irradiation times on the carbon fiber surface was studied and is discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman spectroscopy with ultraviolet excitationJOURNAL OF RAMAN SPECTROSCOPY, Issue 6-7 2005Xu-Feng Lin Abstract Surface-enhanced Raman scattering (SERS) spectroscopy excited with a UV laser was successfully developed and the UV,SER spectra of various adsorbates, including pyridine and SCN,, on different transition metal electrodes were obtained. The experimental requirements for obtaining UV,SERS in an electrochemical system are given. The surface enhancement factor of a roughened Rh electrode covered with thiocyanate as a model molecule was estimated to be about two orders of magnitude in the UV region, consistent with our preliminary theoretical calculation based on the electromagnetic model. The investigation of SERS in the UV region will improve the understanding of the SERS enhancement mechanism and broaden the research field of SERS in areas such as surface science and the life sciences. Copyright © 2005 John Wiley & Sons, Ltd. [source] Adsorption 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] Surface-enhanced Raman scattering of 4,4,-dicyanobiphenyl on gold and silver nanoparticle surfacesJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2002Chung-ro Lee The adsorption behavior of 4,4,-dicyanobiphenyl (DCBP) on Ag and Au nanoparticle surfaces was studied by surface-enhanced Raman scattering (SERS). The absence of the ring CH band denoted a flat orientation of the biphenyl ring on Ag and Au. The red shift of the ,8a band indicated a direct ring ,-orbital interaction with the surfaces. The two benzene rings of DCBP appeared to lie on the same plane with a ,-type interaction upon adsorption on the surfaces. The ,(CN) bands were blue shifted in the Ag and Au SERS spectra by 2 and 22 cm,1, respectively from the ordinary Raman spectrum. The orientation of DCBP on the Ag and Au surfaces was analyzed by the relative enhancement factors of the vibrational bands based on the electromagnetic SERS selection rule. Copyright © 2002 John Wiley & Sons, Ltd. [source] SERS Microscopy: Nanoparticle Probes and Biomedical ApplicationsCHEMPHYSCHEM, Issue 9-10 2009Sebastian Schlücker Prof. Abstract Microspectroscopic imaging: Surface-enhanced Raman scattering (SERS) microscopy is a novel method of vibrational microspectroscopic imaging for the selective detection of biomolecules in targeted research. This review summarizes current designs of nanoparticle-based SERS probes (see figure) and highlights first biomedical applications of SERS microscopy for protein localization ex and in vivo. Surface-enhanced Raman scattering (SERS) microscopy is a novel method of vibrational microspectroscopic imaging for the selective detection of biomolecules in targeted research. This technique combines the advantages of biofunctionalized metal nanoparticles and Raman microspectroscopy for visualizing and quantifying the distribution of target molecules such as proteins in cells and tissues. Advantages of SERS over existing labeling approaches include the tremendous multiplexing capacity, quantification using the characteristic SERS signatures and high photostability. This review summarizes current designs of nanoparticle-based SERS probes and highlights first biomedical applications of SERS microscopy for protein localization ex and in vivo. [source] | |||||||||||||