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Reflection Spectroscopy (reflection + spectroscopy)

Distribution by Scientific Domains
Polymers and Materials Science60%
Chemistry40%

Selected Abstracts

Nanoparticle-Structured Ligand Framework as Electrode Interfaces

ELECTROANALYSIS, Issue 1-2 2004
Nancy
Abstract Nanostructured thin film assemblies derived from metal or oxide nanocrystal cores and functionalized molecular shells provide large surface-to-volume ratio and three-dimensional ligand frameworks. In this article, we report results of an investigation of the nanostructured materials for electroanalysis. Monolayer-capped gold nanoparticles of 2-nm core diameter and carboxylic acid-functionalized alkyl thiols were assembled on electrode surfaces via an exchange-crosslinking-precipitation reaction route, and were studied as a model system. The network assemblies exhibit open frameworks in which the void space forms channels with the nanometer sized cores defining its size and the shell structures defining its chemical specificity. Such nanostructures were exploited to demonstrate the viability of responsive materials for interfacial incorporation and fluxes of ionic species. The nanomaterials were characterized by an array of techniques, including cyclic voltammetry, electrochemical quartz-crystal nanobalance, flow injection analysis, and surface infrared reflection spectroscopy. The current responses and mass loading as a result of the incorporation of ionic species into the nanostructure have been analyzed. The potential application of the nanostructured thin films for electrochemical detection in microfluidic systems is also discussed. [source]

Dimer-Based Three-Dimensional Photonic Crystals

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2010
Ian D. Hosein
Abstract The self-assembly of polystyrene dimer- and spherocylinder-shaped colloids is achieved via controlled drying on glass and silicon substrates. 3D monoclinic colloidal crystal structures are determined from scanning electron microscopy images of sections prepared using focused ion-beam (FIB) milling. Full photonic bandgaps between the eighth and ninth bands are found for a systematic range of colloidal dimer shapes explored with respect to the degree of constituent lobe fusion and radius ratio. The pseudogap between bands 2 and 3 for spherocylinder-based monoclinic crystals is also probed using normal incidence reflection spectroscopy. [source]

Aligning Single-Walled Carbon Nanotubes By Means Of Langmuir,Blodgett Film Deposition: Optical, Morphological, and Photo-electrochemical Studies

ADVANCED FUNCTIONAL MATERIALS, Issue 15 2010
Gabriele Giancane
Abstract An alkoxy-substituted poly(phenylene thiophene) is used in order to suspend single-walled carbon nanotubes in an organic solvent. The suspension is spread on the air,water interface of a Langmuir trough and the floating film is characterized by means of Brewster angle microscopy and UV-visible reflection spectroscopy and the compression isotherm is recorded. The polymer/carbon-nanotube blend is transferred onto different substrates using the Langmuir,Blodgett technique. AFM measurements indicate the formation of globular structures for the samples transferred at low surface-pressure values and a tubular morphology for high-pressure-deposited samples. AFM analysis is repeated on a sample exposed to soft X-rays for about 5,h and a highly organized structure of bundles of carbon nanotubes rises up. Samples with different numbers of layers are transferred onto ITO substrates by means of the Langmuir,Blodgett method and are tested as photocathodes in a photo-electrochemical cell. A Voc of 0.18,V, an Isc of 85.8,mA, FF of 40.0%, and , of (6.23,×,10,3)% are obtained. [source]

Monomer concentration effect on electrochemically modified carbon fiber with poly[1-(4-methoxyphenyl)-1H -pyrrole] as microcapacitor electrode

ADVANCES IN POLYMER TECHNOLOGY, Issue 2 2009
A. Sezai Sarac
Abstract In this study, films of poly[1-(4-methoxyphenyl)-1H -pyrrole] [poly(MPPy)] were electrochemically grown on carbon fiber microelectrodes (CFMEs) in 0.05 M of tetraethyl ammonium perchlorate,dichloromethane. The effect of different monomer concentrations (range = 1,10 mM) on electrochemical properties of resulting polymers was characterized by cyclic voltammetry, Fourier transform infrared reflectance-attenuated total reflection spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. All modified CFMEs were found to have capacitance on the basis of Nyquist, Bode-magnitude, Bode-phase, and Admittance plots. An equivalent circuit model of (R(C(R(QR)))(CR)) gave the best fit for all monomer concentrations used. Furthermore, SEM and AFM results showed that poly(MPPy) was formed as a continuous and well-adhered film onto CFME. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:120,130, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20152 [source]

Investigations on the Photoinitiator-free Photopolymerization of Acrylates by Vibrational Spectroscopic Methods

MACROMOLECULAR SYMPOSIA, Issue 1 2005
Tom Scherzer
Abstract Photopolymerization of acrylates without photoinitiators was carried out by irradiation with short-wavelength UV light from excimer lamps with an emission at 222 or 172 nm. Basic investigations on the reactivity of various acrylates and on the conditions under which they can be UV-cured were performed by real-time FTIR-ATR spectroscopy. Depending on the molar extinction coefficients of a specific acrylate at the wavelength of irradiation, the absorption of the light within the coating leads to a pronounced intensity gradient which significantly influences polymerization rate and conversion. Accordingly, it limits the maximum thickness of the layer that can be cured (ranging from some hundreds of nanometres up to some micrometers). In addition to the basic studies, thin acrylate coatings were also cured on pilot scale. The actual conversion in the layer after UV irradiation was directly monitored by in-line NIR reflection spectroscopy, and the resulting coatings were characterized by FTIR spectroscopy and hardness measurements. [source]