A generalized exponential relationship between the surface-enhanced Raman scattering (SERS) efficiency of gold/silver nanoisland arrangements and their non-dimensional interparticle distance/particle diameter ratio (original) (raw)
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Research Letters in Optics, 2009
Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR) and surface enhanced Raman spectroscopy (SERS) are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticles evaporated on top of larger gold nanoparticles show higher SERS than gold-silver alloyed nanoparticles, in spite of the fact that the SPR peak of alloyed nanoparticles is narrower and closer to the excitation wavelength. The highest Raman enhancement was obtained for substrates with a two-peak particle size distribution for excitation wavelengths close to the SPR.
Plasmonics, 2016
Highly ordered arrays of vertically aligned Au nanorod arrays consisting of agglomerated nanoparticles are fabricated by porous anodic aluminum oxide (AAO) template-assisted electrochemical deposition. The Au nanorod arrays with rough surfaces are then transformed to smooth surfaces by a subsequent thermal annealing step. The surface-enhanced Raman scattering (SERS) intensity of the Au nanorod arrays with rough and smooth surfaces was compared to investigate the morphology dependence of SERS. The Au nanorod arrays with agglomerated structures demonstrated a highly active SERS effect as abundant nanogaps are created uniformly by combination of hot spots caused by both agglomerated porous structures on each nanorod and inter-rod gaps.
Nanomaterials, 2013
Gold and silver nanoparticles (NPs) were prepared in water, acetonitrile and isopropanol by laser ablation methodologies. The average characteristic (longer) size of the NPs obtained ranged from 3 to 70 nm. 4-Aminobenzebethiol (4-ABT) was chosen as the surface enhanced Raman scattering (SERS) probe molecule to determine the optimum irradiation time and the pH of aqueous synthesis of the laser ablation-based synthesis of metallic NPs. The synthesized NPs were used to evaluate their capacity as substrates for developing more analytical applications based on SERS measurements. A highly energetic material, TNT, was used as the target compound in the SERS experiments. The Raman spectra were measured with a Raman microspectrometer. The results demonstrate that gold and silver NP substrates fabricated by the methods developed show promising results for SERS-based studies and could lead to the development of micro sensors.
Raman spectroscopy has enabled researchers to map the specific chemical makeup of surfaces, solutions, and even cells. However, the inherent insensitivity of the technique makes it difficult to use and statistically complicated. When Raman active molecules are near gold or silver nanoparticles, the Raman intensity is significantly amplified. This phenomenon is referred to as surface-enhanced Raman spectroscopy (SERS). The extent of SERS enhancement is due to a variety of factors such as nanoparticle size, shape, material, and configuration. The choice of Raman reporters and protective coatings will also influence SERS enhancement. This review provides an introduction to how these factors influence signal enhancement and how to optimize them during synthesis of SERS nanoparticles.
Surface enhanced Raman scattering from layered assemblies of close-packed gold nanoparticles
Analytica Chimica Acta, 2007
A synthetic method of ordering hydrophilic gold nanoparticles into a close-packed twodimensional array at a hexane-water interface and subsequent transferring of such structure onto a solid substrate is described. By repeating the transfer process, multilayered gold nanoparticle films are formed without need of linker molecules. Their surface enhanced Raman scattering (SERS) efficiencies are compared as a function of the number of layers. It is shown that both the number of layers and the particle size contribute to SERS phenomenon. Judging from the noticeable dependence of SERS efficiency on the nanometer scale architecture, the close-packed nanoparticle formation at an immiscible interface presents a facile route to the preparation of highly active and relatively clean SERS substrates by controlling both the particle size and the film thickness. Among the investigated samples, the gold nanoparticle film assembled with quintuple layers of 30 nm diameter particles showed the maximum SERS efficiency.
Surface-enhanced Raman scattering-active gold nanoparticles modified with a monolayer of silver film
The Analyst, 2012
Gold nanoparticles were produced by photochemical reaction of synchrotron radiation. The gold nanoparticles grew and aggregated into the higher-order nanostructure. The behavior is qualitatively explained by analytical estimation. The surface-enhanced Raman spectroscopy of 4,4 0-bipyridine (4bpy) was demonstrated. The substrate fabricated in a suitable condition provides in situ SERS for 1 nM 4bpy.
Current Nanoscience, 2014
Tea-gold nanosponges (T-Au NSs), tea-silver nanoparticles (T-Ag NPs), and tea-gold/silver nanosponges (T-Au/Ag NSs) synthesized by mixing a tea infusion with gold (silver) ions were demonstrated. UV-Vis spectroscopy, transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and powder X-ray diffraction (XRD) analysis were used to characterize as synthesized nanomaterials. Thereafter, the potential for use of the T-Au NSs, T-Ag NPs, and T-Au/Ag NSs in surface-enhanced Raman scattering (SERS) applications was investigated. The T-Au NSs provided a more intense SERS signal than the T-Ag NPs because of extremely intense local electromagnetic fields. In addition, the SERS enhancement factor for the T-Au NSs was further enhanced when Ag NPs were adsorbed on their surface.