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Total Reflection (total + reflection)
Terms modified by Total Reflection Selected AbstractsInterface of atomic layer deposited Al2O3 on H-terminated siliconPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2006K. Y. Gao Abstract Al2O3 films 1 to 20 nm thick were deposited as alternative high-, gate dielectric on hydrogen-terminated silicon by Atomic Layer Deposition (ALD) and characterized by Synchrotron X-ray Photoelectron Spec-troscopy (SXPS), Fourier Transform Infrared (FTIR) absorption spectroscopy and admittance measure-ments. The SXPS results indicate that about 60% of the original Si,H surface bonds are preserved at the Al2O3/Si interface and this is confirmed by monitoring the Si,H stretching modes by FTIR spectroscopy in the Attenuated Total Reflection (ATR) mode both before and after ALD of Al2O3. The remaining 40% of Si,H bonds are replaced by Si,O bonds as verified by SXPS. In addition, a fraction of a monolayer of SiO2 forms on top of the Al2O3 dielectric during deposition. The presence of OH-groups at a level of 3% of the total oxygen content was detected throughout the Al2O3 layer through a chemically shifted O 1s component in SXPS. Admittance measurements give a dielectric constant of 9.12, but a relatively high density of interface traps between 1011 and 1012 cm,2 eV,1. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigation of interfacial structure of couping agent treated fillers by fourier transform infrared spectroscopy and attenuated total reflection-FTIR spectroscopyPOLYMER COMPOSITES, Issue 1 2002Yujuan Liu The interfacial structures of fillers treated by coupling agents were studied with FTIR and a Attenuated Total Reflection (ATR)-FTIR spectrometer. The interfacial interaction was investigated by FTIR, and the nature of interaction was proved to be a chemical bonding, which could not be destroyed by extraction. Using a variable angle ATR technique, the average interfacial layer thickness of filler treated with different amounts of coupling agent was determined. A calibration curve was obtained from these studies to determine the optimal amount of coupling agent for different fillers, which was in agreement with the results of mechanical tests. ATR-FTIR technique is a convenient method to determine the proper amount of coupling agent in composites. [source] Synchrotron-Based Micro-CT and Refraction-Enhanced Micro-CT for Non-Destructive Materials Characterisation,ADVANCED ENGINEERING MATERIALS, Issue 6 2009Bernd R. Müller Abstract X-ray computed tomography is an important tool for non-destructively evaluating the 3-D microstructure of modern materials. To resolve material structures in the micrometer range and below, high brilliance synchrotron radiation has to be used. The Federal Institute for Materials Research and Testing (BAM) has built up an imaging setup for micro-tomography and -radiography (BAMline) at the Berliner storage ring for synchrotron radiation (BESSY). In computed tomography, the contrast at interfaces within heterogeneous materials can be strongly amplified by effects related to X-ray refraction. Such effects are especially useful for materials of low absorption or mixed phases showing similar X-ray absorption properties that produce low contrast. The technique is based on ultra-small-angle scattering by microstructural elements causing phase-related effects, such as refraction and total reflection. The extraordinary contrast of inner surfaces is far beyond absorption effects. Crack orientation and fibre/matrix debonding in plastics, polymers, ceramics and metal-matrix-composites after cyclic loading and hydro-thermal aging can be visualized. In most cases, the investigated inner surface and interface structures correlate to mechanical properties. The technique is an alternative to other attempts on raising the spatial resolution of CT machines. [source] Novel mechanism for hair shine with special optical enhancement effect on blonde hairINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2010S. Iwai J. Cosmet. Sci., 60, 323,336 (May/June 2009) Accepted for publication October 21, 2008. Synopsis Compared with dark or brunette hair, blonde hair has different characteristic features of appearance such as bright shine with a soft tonal color. In this report, novel optical mechanisms of the characteristic blonde hair appearance are reported. Optical analyses of goniophotometric measurements were carried out to elucidate the mechanisms of strong reflections observed in blonde hairs. As a result, reflections with much higher intensity than those from the front surface of a fiber were confirmed to play important roles in the case of blonde hair fibers, and the intensities were found to vary with the cross-sectional shape of a fiber, the ellipticity (=minor axis/major axis). From light path simulation analyses, these strong reflections were verified to result from total reflection from the back surface of a fiber. Furthermore, since each hair fiber acts as a lens and/or a reflector, intricate reflection behaviors are suggested to occur as a consequence of the combination of light condensation and total reflection. [source] Hierarchical principal component analysis (PCA) and projection to latent structure (PLS) technique on spectroscopic data as a data pretreatment for calibrationJOURNAL OF CHEMOMETRICS, Issue 4 2001K. Janné Abstract Spectroscopic data consists of several hundred to some thousand variables, wherein most of the variables are autocorrelated. When PCA and PLS techniques are used for the interpretation of these kinds of data, the loading plots are usually complex due to the covariation in the spectrum, and therefore difficult to correlate to the corresponding score plot. One of the standard methods used to decrease the influence of light scatter or shifts of the spectra is the multiplicative scatter correction technique. Another technique is the hierarchical multiblock segmentation technique, where new variables are created from the original data by blocking the spectra into sub spectra, and then projecting the sub spectra by PCA. These new variables are then used in the coming PCA or PLS calculations. These techniques reduce the random and non-wanted signals from e.g. light scatter, but still conserve all systematic information in the signals, but the greatest advantage is that the technique gives an easier interpretation of the correlation between scores and the loadings. Two examples are presented; the attenuated total reflection (ATR) and NIR, which show the advantages as well as the implementation of the method. Copyright © 2001 John Wiley & Sons, Ltd. [source] Wide area illumination Raman scheme for simple and nondestructive discrimination of seawater cultured pearlsJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2009Seok Chan Park Abstract Raman spectroscopy, along with discriminant partial least squares (PLS), was successfully used to discriminate among three different groups of cultured pearls (fresh water, Akoya and South seawater). The discrimination between Akoya and South seawater pearls using XRF (X-ray fluorescence), one of the most frequently adopted analytical methods in pearl analysis, has been especially difficult owing to their similar mineral compositions. The selective Raman features helped in effectively discriminating between these two pearl groups. The difference in the intensities of the CaCO3 bands of Akoya and South seawater pearls provided a valuable clue. Along with the selective Raman feature, a reproducible Raman spectral collection achieved using a wide area illumination (WAI) scheme played an important role in the determination of the pearl groups, although the pearls were hard-surfaced, round, solid samples of different sizes and surface shapes. Unwanted spectral variation originating from sensitivity to sample placement relative to the focal plane and from unsuccessful sample representation due to the probing of a localized area, factors that could possibly deteriorate Raman reproducibility, were substantially lessened using the WAI scheme. ATR (attenuated total reflection) IR spectroscopy requiring direct contact with the pearl could be inadequate for discrimination or classification where large numbers of repeating and reproducible measurements are required. Copyright © 2009 John Wiley & Sons, Ltd. [source] Yellow pigments in painting: characterisation and UV laser-induced modificationsJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2009S. Acquaviva Abstract Artistic yellow pigments, commonly employed from antiquity, were investigated by morphological, spectrophotometric and compositional analyses. Namely, scanning electron microscopy,energy dispersive X-ray (SEM/EDX) characterisations and reflectance, attenuated total reflection,Fourier transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy were carried out on egg yolk tempera models to discriminate the pigments. The models were irradiated with excimer KrF (248 nm) laser at different working conditions, and the effects induced on colour were related to chemical and physical modifications through the same analyses, as a function of laser parameters. It came out that the effects on the pictorial layers are always related to the modifications of the binding medium and, in addition, the laser radiation induces dehydration and transformation of iron oxides in natural earths. Copyright © 2009 John Wiley & Sons, Ltd. [source] The new diffractometer for surface X-ray diffraction at beamline BL9 of DELTAJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2006Christof Krywka The experimental endstation of the hard X-ray beamline BL9 of the Dortmund Electron Accelerator is equipped with a Huber six-circle diffractometer. It is dedicated to grazing-incidence X-ray diffraction and X-ray reflectivity experiments on solid surfaces and thin films as well as to powder diffraction measurements. A new set-up for grazing-incidence X-ray scattering of liquids has been built up using a silicon mirror to reflect the incident X-ray to the liquid surface at angles of incidence around the critical angle of total reflection of the sample. X-ray reflectivity measurements of a polymer film and grazing-incidence X-ray diffraction measurements of an epitaxically grown Gd40Y60 film, an oxidized surface of Fe-15at.%Al alloy and aqueous salt solutions are presented and discussed. [source] Vibrational Spectroscopic Studies on the Disulfide Formation and Secondary Conformational Changes of Captopril,HSA Mixture after UV-B IrradiationPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2005Mei-Jane Li ABSTRACT The effects of pH and ultraviolet-B (UV-B) irradiation on the secondary structure of human serum albumin (HSA) in the absence or presence of captopril were investigated by an attenuated total reflection (ATR)/Fourier transform infrared (FTIR) spectroscopy. The UV-B exposure affecting the stability of captopril before and after captopril,HSA interaction was also examined by using confocal Raman microspectroscopy. The results indicate that the transparent pale-yellow solution for captopril,HSA mixture in all pH buffer solutions, except pH 5.0,7.0, changed into a viscous form then a gel form with UV-B exposure time. The secondary structural transformation of HSA in the captopril,HSA mixture with or without UV-B irradiation was found to shift the maxima amide I peak in IR spectra from 1652 cm,1 assigned to ,-helix structure to 1622 cm,1 because of a ,-sheet structure, which was more evident in pH 3.0, 8.0 or 9.0 buffer solutions. The Raman shift from 1653 cm,1 (,-helix) to 1670 cm,1 (,-sheet) also confirmed this result. Captopril dissolved in distilled water with or without UV-B irradiation was determined to form a captopril disulfide observed from the Raman spectra of 512 cm,1, which was exacerbated by UV-B irradiation. There was little disulfide formation in the captopril,HSA mixture even with long-term UV-B exposure, but captopril might interact with HSA to change the protein secondary structure of HSA whether there was UV-B irradiation or not. The pH of the buffer solution and captopril,HSA interaction may play more important roles in transforming the secondary structure of HSA from ,-helix to ,-sheet in the corresponding captopril,HSA mixture than UV-B exposure. The present study also implies that HSA has the capability to protect the instability of captopril in the course of UV-B irradiation. In addition, a partial unfolding of HSA induced by pH or captopril-HSA interaction under UV-B exposure is proposed. [source] High-resolution study of dynamical diffraction phenomena accompanying the Renninger (222/113) case of three-beam diffraction in siliconACTA CRYSTALLOGRAPHICA SECTION A, Issue 4 2010A. Kazimirov X-ray optical schemes capable of producing a highly monochromatic beam with high angular collimation in both the vertical and horizontal planes have been evaluated and utilized to study high-resolution diffraction phenomena in the Renninger (222/113) case of three-beam diffraction in silicon. The effect of the total reflection of the incident beam into the nearly forbidden reflected beam was observed for the first time with the maximum 222 reflectivity at the 70% level. We have demonstrated that the width of the 222 reflection can be varied many times by tuning the azimuthal angle by only a few µrad in the vicinity of the three-beam diffraction region. This effect, predicted theoretically more than 20 years ago, is explained by the enhancement of the 222 scattering amplitude due to the virtual two-stage 000 113 222 process which depends on the azimuthal angle. [source] Vibrational spectroscopic studies to acquire a quality control method of Eucalyptus essential oils,BIOPOLYMERS, Issue 5 2005M. Baranska Abstract This article presents a novel and original approach to analyze in situ the main components of Eucalyptus oil by means of Raman spectroscopy. The obtained two-dimensional Raman maps demonstrate a unique possibility to study the essential oil distribution in the intact plant tissue. Additionally, Fourier Transform (FT)-Raman and attenuated total reflection (ATR)-IR spectra of essential oils isolated from several Eucalyptus species by hydrodistillation are presented. Density Functional Theory (DFT) calculations were performed in order to interpret the spectra of the essential oils of the Eucalyptus species. It is shown that the main components of the essential oils can be recognized by both vibrational spectroscopic techniques using the spectral information of the pure terpenoids. Spectroscopic analysis is based on the key bands of the individual volatile substances and therefore allows one to discriminate different essential oil profiles of several Eucalyptus species. It has been found that the presented spectroscopic data correlate very well with those obtained by gas chromatography (GC) analysis. All these investigations are helpful tools to generate a fast and easy method to control the quality of the essential oils with vibrational spectroscopic techniques in combination with DFT calculations. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 237,248, 2005 [source] Hydrogen-deuterium exchange in membrane proteins monitored by IR spectroscopy: A new tool to resolve protein structure and dynamicsBIOPOLYMERS, Issue 1-2 2004C. Vigano Abstract As more and more high-resolution structures of proteins become available, the new challenge is the understanding of these small conformational changes that are responsible for protein activity. Specialized difference Fourier transform infrared (FTIR) techniques allow the recording of side-chain modifications or minute secondary structure changes. Yet, large domain movements remain usually unnoticed. FTIR spectroscopy provides a unique opportunity to record 1H/2H exchange kinetics at the level of the amide proton. This approach is extremely sensitive to tertiary structure changes and yields quantitative data on domain/domain interactions. An experimental setup designed for attenuated total reflection and a specific approach for the analysis of the results is described. The study of one membrane protein, the gastric H+,K+ -ATPase, demonstrates the usefulness of 1H/2H exchange kinetics for the understanding of the molecular movement related to the catalytic activity. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004 [source] Induction and Inhibition of Preferential Enrichment by Controlling the Mode of the Polymorphic Transition with Seed CrystalsCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2006Rui Tamura Prof. Abstract Both induction and inhibition of "preferential enrichment", an unusual symmetry-breaking enantiomeric-resolution phenomenon observed upon simple recrystallization of a certain kind of racemic crystals from organic solvents, have been successfully achieved by controlling the mode of the polymorphic transition during crystallization with appropriate seed crystals. Such control of the polymorphic transition can be interpreted in terms of a novel phenomenon consisting of 1) the adsorption of prenucleation aggregates, 2) the heterogeneous nucleation and crystal growth of a metastable crystalline form, and 3) the subsequent polymorphic transition into the more stable form; these three processes occur on the same surface of a seed crystal. We refer to this phenomenon as an "epitaxial transition", which has been confirmed by means of in situ attenuated total reflection (ATR) FTIR spectroscopy in solution and the solid state, differential scanning calorimetry (DSC) measurements of the deposited crystals, and X-ray crystallographic analysis of the single crystals or the direct-space approach employing the Monte Carlo method with the Rietveld refinement for the structure solution from the powder X-ray diffraction data. [source] | |||||||||||||