Methods for Describing the Electromagnetic Properties of Silver and Gold Nanoparticles
Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113. Accounts of Chemical Research
(Impact Factor: 22.32).
09/2008; 41(12):1710-20. DOI: 10.1021/ar800028j
This Account provides an overview of the methods that are currently being used to study the electromagnetics of silver and gold nanoparticles, with an emphasis on the determination of extinction and surface-enhanced Raman scattering (SERS) spectra. These methods have proven to be immensely useful in recent years for interpreting a wide range of nanoscience experiments and providing the capability to describe optical properties of particles up to several hundred nanometers in dimension, including arbitrary particle structures and complex dielectric environments (adsorbed layers of molecules, nearby metal films, and other particles). While some of the methods date back to Mie’s celebrated work a century ago, others are still at the forefront of algorithm development in computational electromagnetics.
Available from: A. Amarjargal
- "Plasmonic nanostructures of noble metals such as silver and gold exhibit a phenomenon known as surface-enhanced Raman scattering (SERS) which is based on the strong amplification of the scattering cross-section of molecules absorbed thereon  . There are two mechanisms to such an enormous enhancement of SERS: electromagnetic enhancement that is associated with the localized surface plasmon resonances occurring at the surfaces of roughened metal substrates or metal clusters and chemical enhancement which is associated with the direct charge transfer or indirect electron–hole pair excitation processes  . In the pastdecades, research on SERS which is recognized as one of the most modern laser spectroscopic techniques holds great promise for the fields of analytical chemistry, forensics, food safety, threat detection , and medical diagnostics and the reported detection limit has reached the single molecule level due to its high level detection sensitivity and specificity. "
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ABSTRACT: In this study, by utilizing a two-step route of electrospinning and polyol immersion, in the absence of any surfactant or sensitizing and stabilizing reagent, a well-distributed assembly of Ag NPs on the electrospun polyurethane (PU) nanofibers was successfully fabricated through a simple and controllable manner. Based on the FE-SEM, XRD and FT-IR analyses, the polyol medium plays an important role in the growth of highly monodispersed Ag NPs, wherein the hydroxyl group of ethylene glycol (EG) can be bridged to the amide group on the surface of the PU nanofibers through intermolecular hydrogen bonds. Fabrication of a polymer fibrous membrane effectively attached/decorated with noble metal NPs, which is essential as flexible and high efficiency substrates for SERS application where the molecule analytes are directly adsorbed on their surfaces is important, could be realized by the present electrospun PU-Ag(EG) nanofibers, employing 4-mercaptobenzoic acid (4-MBA) as probe molecules.
Available from: Jitraporn Vongsvivut
- "Gold nanoparticles (GNPs) with diameters ranging from 1 to 100 nm possess unique size and shape dependent physical and chemical properties providing advantages over normal gold materials. Localized surface plasmon resonance (LSPR), caused by the collective oscillation of free electrons in the conduction band on the surface of nanoparticles, is one of the most important properties of the GNPs and other noble metal nanoparticles  . LSPR of the noble metal nanoparticles, which is related to the shape, compositions, and size of nanoparticles, as well as the local refractive index surrounding the particles, has been investigated to develop platforms for the plasmonic sensing of biological and chemical analytes  . "
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ABSTRACT: Molecule-coated nanoparticles are hybrid materials which can be engineered with novel properties. The molecular coating of metal nanoparticles can provide chemical functionality, enabling assembly of the nanoparticles that are important for applications, such as biosensing devices. Herein, we report a new self-assembly of core-satellite gold nanoparticles linked by a simple amino acid l-Cysteine for biosensing of Cu(2+). The plasmonic properties of core-satellite nano-assemblies were investigated, a new red shifted absorbance peak from about 600 to 800nm was found, with specific wavelength depending on ratios with assembly of large and small gold nanoparticles. The spectral features obtained using surface-enhanced Raman spectroscopy (SERS) provided strong evidence for the assembly of the Cu(2+) ions to the L-Cysteine molecules leading to the successful formation of the core-satellite Cu(l-Cysteine) complex on the gold surfaces. In addition, a linear relationship between the concentration of mediating Cu(2+) and absorbance of self-assembled gold nanoparticles (GNPs) at 680nm was obtained. These results strongly address the potential strategy for applying the functionalized GNPs as novel biosensing tools in trace detections of certain metal ions.
Available from: Jiadong Zhou
- "In this simulation, both the radius of the VO2 particle and the distance between two particles are 100 nm. The scattering of normal incident light in a wavelength range of 350–780 nm along the z-direction and polarised along the y/x-direction was simulated25 (Figure 2a). The far field angular scattering shown in Figure 2b suggests that the scattering field intensity extended to a far zone, which means the scattering field is obvious and large. "
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ABSTRACT: The ability to achieve energy saving in architectures and optimal solar energy utilisation affects the sustainable development of the human race. Traditional smart windows and solar cells cannot be combined into one device for energy saving and electricity generation. A VO2 film can respond to the environmental temperature to intelligently regulate infrared transmittance while maintaining visible transparency, and can be applied as a thermochromic smart window. Herein, we report for the first time a novel VO2-based smart window that partially utilises light scattering to solar cells around the glass panel for electricity generation. This smart window combines energy-saving and generation in one device, and offers potential to intelligently regulate and utilise solar radiation in an efficient manner.
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