Papers by Keyword: Surface Enhanced Raman Scattering

Abstract: The rapid progress of nanotechnology has created new avenues for the development of innovation in medical and biological devices. Transition metal dichalcogenides (TMDs) nanostructures such as tungsten disulfide nanodiscs (WS₂-NDs) decorated with metallic nanoparticles, provide promising novel materials for surface Enhanced Raman Spectroscopy (SERS). This work focuses on the design and fabrication of a new SERS substrate based on AuNPs/WS₂-NDs hybrid system, which exhibits a strong localized surface plasmonic resonance (LSPR) and achieves up to an order of magnitude enhancement in Raman spectra intensity compared to WS₂-NDs only. This superior performance is attributed to the improved electromagnetic mechanism (EM) on the metallic gold nanoparticles and on the nonmetallic TMDs nanostructures. The chemical mechanism (CM), which facilitates charge transfer between analyte molecules and WS₂-NDs, allows for further improvement of Raman spectra on SERS on tungsten disulfide nanodiscs.

Abstract: Quasiperiodic microstructures are formed on the surfaces of metals under irradiation with high-power femtosecond laser pulses. Interpretation of microstructures as a result of interference of the incident plane wave and surface waves leads to the logical conclusion about the relationship of dislocations in the interference fringes with optical vortices in surface wave. Other peculiarities observed in these structures contain different periods and nanogranular fine structure. It is demonstrated that such laser-induced structures can find applications for surface plasmon excitation and surface enhanced Raman scattering.

Abstract: Molecular recognition of specific DNA target is crucial for species authentication, drug discovery, forensic investigation and biodiagnostics. Development of nanoparticles at atomic scale and molecular level offers remarkable biocompatibility in the detection of DNA hybridization. Oligo-functionalized nanoparticles with controlled sizes and shapes have come forward with advantages over the previously documented DNA detection assays. Nanomaterials facilitate signal transduction and synergism in biomolecular interaction, promoting both conventional and newly developed DNA identification platforms. Tailoring of DNA sensing tools with gold nanoparticles (Au NPs) enhances the Surface Enhanced Raman Scattering (SERS) signal, allowing target detection with molecular precision. Here we briefly reviewed the recent AuNPs based SERS-platforms for the specific, sensitive and reliable detection of DNA targets for species authentication in foods and feeds.

Abstract: The highly ordered silver nanowire arrays were fabricated successfully by an easily produced and handled approach with the assistance of nanoporous anodized aluminum oxide(AAO) template. The silver nanowires with uniform diameters are highly ordered and parallel to each other. A broad UV-visible absorption band with a center at 401nm of silver nanowire arrays were detected. Optimized surface enhanced Raman scattering(SERS) signals of crystal violet molecules(CV) were recorded. It was found that the substrate exhibits strong enhancement properties due to the surface plasma resonance(SPR) of highly ordered silver nanowire arrays. The enhancement factor was calculated as 3.5×106. In addition, the results offered a simple technique in preparing highly ordered nanowire arrays which can be used as negative-refractive-index material as well as excellent SERS substrate.

Abstract: Surface-enhanced Raman scattering (SERS) integrates high levels of sensitivity with spectroscopic precision and thus has tremendous potential for chemical and biomolecular sensing. The key to the wider application of Raman spectroscopy using roughened metallic surfaces is the development of highly enhancing substrates for analytical purposes, i.e., for better detection sensitivity of tracing contaminants and pollutants. Controlled methods for preparing nano-structured metals may provide more useful correlations between surface structure and signal enhancement. Here, we self-assembled silver nanorods on glass substrates for sensitive SERS substrates. The enhanced surface Raman scattering signals were observed and mainly attributed to the local field enhancement.

Abstract: Ultrahigh-Quality microcavity with whispering-gallery-mode (WGM) is a new kind of resonator with high quality. The evanescent wave of WGM plays an important role in surface enhanced Raman scattering (SERS). In this paper we study the relationship between coupling coefficient and evanescent wave of the WGM and the coupling character difference between the microsphere and the microstadium. Based on the finite-difference time-domain (FDTD), we calculate the coupling coefficient of different substances (water, C2H5OH, CHCL3, olive oil, C6H6 and CS2) with different dielectric constant and the mode volume ratio of the evanescent wave in microsphere and microstadium of the above substances in near field. The results show that (1) the mode volume ratio of evanescent wave will decrease with the increasing of the coupling coefficient; (2) the microstadium has a higher coupling coefficient than the sphere one.