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Wavelength Region (wavelength + region)
Selected AbstractsCrystal growth, crystal structure and physical properties of polar orthorhombic tris(glycine) zinc chlorideCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2008M. Fleck Abstract Large single crystals of the polar (point group mm 2) compound tris(glycine) zinc chloride, (NH3CH2COO)3 · ZnCl2, were grown from aqueous solutions. The refractive indices were measured in the wavelength region from 365 nm to 1083 nm and an unpolarised absorption spectrum was recorded (transparency range from 260 to 1550nm). The phase matching conditions for second harmonic generation were analysed: both, type I (ss-f) and type II (sf-f) are possible in the red and near IR region. All five components of the piezoelectric tensor [dijk ] were determined; the maximum values of longitudinal and transverse piezoelectric effects are less than one half of d111 of ,-quartz. In addition, a redetermination of the crystal structure (including location of H atoms) is presented. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Metal-Free Alkyne Polyhydrothiolation: Synthesis of Functional Poly(vinylenesulfide)s with High Stereoregularity by Regioselective Thioclick PolymerizationADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Cathy K. W. Jim Abstract A new synthetic route to sulfur-rich polymers has been developed. The alkyne polyhydrothiolations of 4,4,-thiodibenzenethiol (1) and arylene dipropiolates (2,5) mediated by amines proceed at room temperature in a regioselective fashion, furnishing sole anti-Markovnikov products of poly(vinylenesulfide)s (P1/2,P1/5) with high molecular weights (Mw up to 32 300) and high stereoregularities (Z content up to 81.4%) in high yields (up to 98.2%). Polymers P1/2,P1/4 are soluble in common organic solvents. They are optically transparent, allowing almost all visible and IR light to transmit through. Thanks to the high sulfur contents of the polymers, their films show high refractive indices (n,=,1.73,1.70) in the wavelength region of 500,1700 nm as well as high Abbé numbers (,D' up to 539) and low optical dispersions (D' down to 0.002) at wavelengths important for telecommunications. Their refractivities can be further enhanced (n up to 2.06) by metal complexation and their films can be crosslinked by UV irradiation, which enables ready fabrication of fluorescent photopatterns. [source] Metal-Free Click Polymerization: Synthesis and Photonic Properties of Poly(aroyltriazole)sADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Anjun Qin Abstract Regioselective 1,3-dipolar polycycloadditions of tetraphenylethene (TPE)-containing diazides 1,3 and bis(aroylacetylene) 4 are initiated by simple heating, affording poly(aroyltriazole)s (PATAs) PI,PIII with high molecular weights in high yields. The PATAs are completely soluble in common organic solvents and stable at temperatures up to 358,°C. Thanks to their TPE units, the polymers show aggregation-induced emission and work as explosive sensors with high sensitivity. The PATAs are optically transparent in the whole visible spectral region. Their refractive indexes can be tuned to a great extent (,n,,,0.08) by simply changing their alkyl spacer lengths. The modified Abbé numbers of the PATAs are very high (up to 273), indicative of very low optical dispersions in the telecommunication-important wavelength region. UV irradiation through a photomask quenches the light emissions of the polymers, enabling the generation of two-dimensional fluorescent images without development. The polymers can be readily photo-crosslinked, yielding three-dimensional patterns with high resolutions. [source] Highly Non-Linear Quantum Dot Doped Nanocomposites for Functional Three-Dimensional Structures Generated by Two-Photon PolymerizationADVANCED MATERIALS, Issue 22 2010Baohua Jia A nanocomposite consisting of a photosensitive organic,inorganic hybrid polymer functionalized with PbS quantum dots has been developed using a sol,gel process. The uniformly dispersed nanocomposite exhibits ultrahigh third-order non-linearity (,3.2,×,10,12 cm2 W,1) because of the strong quantum confinement of small-sized and narrowly distributed quantum dots. The non-linear nanocomposite has been proven to be suitable for the fabrication of 3D micro/nano photonic devices using two-photon polymerization. The fabricated photonic crystals show stop gaps with more than 60% suppression in transmission at the telecommunications wavelength region. [source] Monitoring Delamination Progression in Thermal Barrier Coatings by Mid-Infrared Reflectance ImagingINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2006Jeffrey I. Eldridge Mid-infrared (MIR) reflectance imaging is shown to be a reliable diagnostic tool for monitoring delamination progression in thermal barrier coatings (TBCs). MIR reflectance imaging utilizes the maximum transparency of TBCs in the 3,6 ,m wavelength region to probe below-surface delamination crack propagation that is typically hidden from visible wavelength inspection. The image contrast that identifies delamination progression arises from the increased reflectance produced by a large component of total internal reflection at the TBC/buried-crack interface. Imaging was performed at a wavelength of 4 ,m to take advantage of the relatively high transmittance of plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) TBCs along with a desirable relative insensitivity to potentially interfering absorptions by atmospheric constituents at that wavelength. A key advantage of MIR reflectance imaging over competing techniques is that it is sensitive to delamination progression even at very early stages before delamination cracks start linking together; therefore, TBC health assessment can be achieved throughout the life of the TBC well before TBC failure is imminent. Examples are presented to demonstrate monitoring delamination progression by MIR reflectance imaging in 8YSZ TBC-coated specimens subjected to furnace cycling to 1163°C. The experimental results were in good agreement with reflectance values predicted by a four-flux Kulbelka,Munk approximation applied to the extreme cases of a completely adherent and a completely detached TBC. Practical considerations, including potential interfering effects from surface contamination, sintering, and erosion are discussed. [source] Translucent ,-Sialon Ceramics by Hot PressingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2004Xinlu Su The single-phase ,-sialon ceramics with high optical transmittance have been prepared by hot pressing. The maximum transmittance reached 65.2% and 52.2% in the infrared wavelength region, 58.5% and 40% in the visible region for the samples 1.0 and 1.5 mm thickness, respectively. The material also exhibited good mechanical properties of high hardness (20 GPa) and better fracture toughness (5.1 MPa·m1/2). Both high optical transmittance and improved toughness of ,-sialon ceramics were attributed to the less-grain-boundary glassy phase and the homogeneous microstructure, which was obtained by a proper process and confirmed by SEM and TEM observation, compared to that prepared by ordinary sintering. It is, therefore, expected that the translucent ,-sialon ceramics could be a promising optical window material. [source] Fabrication of Arsenic Selenide Optical Fiber with Low Hydrogen ImpuritiesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2002Vinh Q. Nguyen Arsenic selenide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of 0.1 wt% tellurium tetrachloride (TeCl4) to the glass. During melting, the chlorine from TeCl4 reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to give very low H,Se impurity content. Consequently, the H,Se absorption band centered at 4.57 ,m has been reduced from tens of dB/m to 0.2 dB/m. [source] Fabrication of Arsenic Sulfide Optical Fiber with Low Hydrogen ImpuritiesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2002Vinh Q. Nguyen Arsenic sulfide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of tellurium tetrachloride (TeCl4) to the glass. During melting, the chlorine from TeCl4 reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to produce optical fibers with significantly reduced loss due to hydrogen sulfide impurity content (1.5 dB/m). [source] An efficient gain-flattened C-band Erbium-doped fiber amplifierLASER PHYSICS LETTERS, Issue 11 2006S. W. Harun Abstract An efficient gain-flattened C-band Erbium-doped fibre amplifier is demonstrated using a double-pass configuration with an IsoGainTM Erbium-doped fibre (EDF). The amplifier utilizes a double-propagation of signal provided by an optical circulator at the output end of the EDF to obtain an improved flatgain characteristic. At input signal power of ,10 dBm, a flatgain of 25 dB was obtained from wavelength region from 1528 to 1568 nm. This amplifier has the potential to be used in the high channel count dense wavelength division multiplexing system because of its simplicity and low cost. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Spectral properties of angritesMETEORITICS & PLANETARY SCIENCE, Issue 8 2006T. H. Burbine Almost all angrites (e.g., D'Orbigny, Lewis Cliff [LEW] 86010, and Sahara 99555) are composed predominately of anorthite, Al-Ti diopside-hedenbergite, and Ca-rich olivine, except for the type specimen, Angra dos Reis, which is composed almost entirely of Al-Ti diopside-hedenbergite. D'Orbigny, LEW 86010, and Sahara 99555 also have spectral properties very different from Angra dos Reis. These newly measured angrites all have broad absorption features centered near 1 ,m with very weak to absent absorption bands at ,2 ,m, which is characteristic of some clinopyroxenes. The spectrum of Angra dos Reis has the characteristic 1 and 2 ,m features due to pyroxene. One asteroid, 3819 Robinson, has similar spectral properties to the newly measured angrites in the visible wavelength region, but does not appear to spectrally match these angrites in the near-infrared. [source] Optical fiber sensor for localizing heating positions in multiple points using multichannel gratings with phase sampling and wavelength division multiplexing techniquesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2008Li Xia Abstract An optical fiber sensor system with multichannel fiber Bragg gratings (FBGs) is proposed. The gratings are designed and fabricated by phase sampling technique within strongly chirped phase masks. The sensing application can be realized at multiple points through wavelength division multiplexing (WDM) technique. It means that the different point can be monitored by different gratings, which occupies different wavelength region, according to the central pitch and chirp coefficient of phase masks. The heating position with high resolution can be analyzed through three corresponding channel shifts in the multichannel profile. In our experiment, the two multichannel gratings with channel spacing of 0.8 and 1.6 nm, respectively, are fabricated and used for sensing in two points. At last, the 400 ,m accuracy of localizing the heating position is achieved. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2951,2954, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23832 [source] High-performance UV emitter grown on high-crystalline-quality AlGaN underlying layerPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2009Hirotoshi Tsuzuki Abstract Al0.25Ga0.75N films were grown on a grooved-Al0.25Ga0.75N/ AlN/sapphire template by MOVPE. The dislocation density on the grooved areas was as low as 1 × 108 cm,2. We fabricated a UVA light-emitting diode grown on such an AlGaN underlying layer exhibiting an output power of 12 mW at a DC current of 50 mA with a peak emission wavelength of 345 nm, which corresponds to an external quantum efficiency of 6.7%. This efficiency is the highest reported to date in this wavelength region. We also fabricated a 358 nm UVA laser diode (LD) using a GaN/AlGaN MQW active layer grown on an AlGaN underlying layer. This UV LD exhibits a threshold current of 73 mA and a corresponding current density of 3.8 kA/cm2 at 7 °C. The characteristic temperature T0 was 174 K in the temperature range of 7,27 °C. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Refractive index of TlGaAsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2008K. Ohnishi Abstract Refractive index has been determined from reflectance measurements at 77-300 K for Tlx Ga1,xAs samples with x , 0.077 prepared by low-temperature molecular-beam epitaxy. A very high refractive index of around 4.5 at room temperature in the transparent wavelength region has been revealed for Tlx Ga1,xAs with x = 0.077. The temperature coefficient of the refractive index was found to increase with Tl content. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ion irradiation and reduction effect on the conductivity and optical absorption of heavily MgO-doped LiNbO3 single crystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005V.F. Pichugin Abstract The confirmation of MgNb defects in heavily MgO doped LiNbO3 single crystals were investigated through optical absorption, electrical conductivity measurements, optical spectroscopy with nanosecond time resolution, and Raman spectroscopy technique. An increase in the MgO concentration up to 10 mole% provides an essential change of the luminescence of LiNbO3, the appearance of a supplementary optical absorption band at the 1.1 eV, an alteration of the Raman spectra caused by the formation of (MgNb) defects, a shift of the edge of the supplementary optical absorption due to ion irradiation toward the shorter wavelength region as the MgO concentration increases. The effect of Ar+ ions irradiation on the conduction of the MgO doped LiNbO3 samples was studied. The important role of reduction in modification of the conducting properties of the ion-irradiated crystals was established. The increase of the MgO concentration leads to a decrease of the reduction efficiency. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical properties of thin-film silicon solar cells with grating couplersPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2006C. Haase Abstract The effect of grating couplers on the optical properties of silicon thin-film solar cells was studied by a comparison of experimental results with numerical simulations. The thin-film solar cells studied are based on microcrystalline silicon (,c-Si:H) absorber layers of thickness in the micrometer range. To investigate the light propagation in these cells, especially in the red wavelength region, three-dimensional power loss profiles are simulated. The influence of different grating parametres,such as period size, groove height, and shape of the grating,was studied to gain more insight into the light propagation within thin-film silicon solar cells and to determine an optimized light trapping scheme. The effect of the TCO front and TCO back side layer thickness was investigated. The calculated quantum efficiencies and short-circuit current densities are in good agreement with the experimental data. The simulations predict further optimization criteria. Copyright © 2006 John Wiley & Sons, Ltd. [source] Highly-efficient Cd-free CuInS2 thin-film solar cells and mini-modules with Zn(S,O) buffer layers prepared by an alternative chemical bath processPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 6 2006A. Ennaoui Abstract Recent progress in fabricating Cd- and Se-free wide-gap chalcopyrite thin-film solar devices with Zn(S,O) buffer layers prepared by an alternative chemical bath process (CBD) using thiourea as complexing agent is discussed. Zn(S,O) has a larger band gap (Eg,=,3·6,3·8,eV) than the conventional buffer material CdS (Eg,=,2·4,eV) currently used in chalcopyrite-based thin films solar cells. Thus, Zn(S,O) is a potential alternative buffer material, which already results in Cd-free solar cell devices with increased spectral response in the blue wavelength region if low-gap chalcopyrites are used. Suitable conditions for reproducible deposition of good-quality Zn(S,O) thin films on wide-gap CuInS2 (,CIS') absorbers have been identified for an alternative, low-temperature chemical route. The thickness of the different Zn(S,O) buffers and the coverage of the CIS absorber by those layers as well as their surface composition were controlled by scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray excited Auger electron spectroscopy. The minimum thickness required for a complete coverage of the rough CIS absorber by a Zn(S,O) layer deposited by this CBD process was estimated to ,15,nm. The high transparency of this Zn(S,O) buffer layer in the short-wavelength region leads to an increase of ,1,mA/cm2 in the short-circuit current density of corresponding CIS-based solar cells. Active area efficiencies exceeding 11·0% (total area: 10·4%) have been achieved for the first time, with an open circuit voltage of 700·4,mV, a fill factor of 65·8% and a short-circuit current density of 24·5,mA/cm2 (total area: 22·5,mA/cm2). These results are comparable to the performance of CdS buffered reference cells. First integrated series interconnected mini-modules on 5,×,5,cm2 substrates have been prepared and already reach an efficiency (active area: 17·2,cm2) of above 8%. Copyright © 2006 John Wiley & Sons, Ltd. [source] The short history of infrared space telescopesASTRONOMISCHE NACHRICHTEN, Issue 6 2009D. Lemke Abstract While astronomical telescopes developed rather slowly over the last four centuries, infrared telescopes made a fast career in only four decades from high mountains to aircraft, balloons and satellites. They cover the huge wavelength region from 1 to 350 , m and have uncovered the cold and dust hidden universe. While until today all infrared space telescopes had diameters of <1 m, cooled infrared observatories with 3.5 to 6.5m mirrors will be sent into heliocentric orbits at L2 within the next few years (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Determination of rat hepatocellular glutathione by reversed-phase liquid chromatography with fluorescence detection and cytotoxicity evaluation of environmental pollutants based on the concentration changeBIOMEDICAL CHROMATOGRAPHY, Issue 4 2001Toshimasa Toyo'oka Three methods for the determination of rat hepatocellular thiols by high-performance liquid chromatography (HPLC) with fluorescence (FL) detection have been developed. The thiols in the cells were tagged with three fluorogenic reagents, SBD-F, ABD-F and DBD-F. These reagents could permeate into cells and effectively reacted with thiols to produce highly fluorescent derivatives. These derivatives fluoresced in the long wavelength region at around 530,nm (excitation at around 380 nm). The five biological thiols tagged were perfectly separated by reversed-phase liquid chromatography and were sensitively and selectively detected without any interference from endogenous substanaces. The main thiol in the cells was reduced GSH and the concentration was at the,mM level. The proposed procedures were applied to the determination of hepatocellular GSH after treatment of environmental pollutants such as volatile organic compounds (VOC) and endocrine disrupting chemicals (EDC). From the comparison of intracellular GSH concentration, the test compounds were classified into four groups: compounds of strong depletion (eg triphenyltin chloride, hexachlorocyclohexene, nonylphenol, bromoacetic acid, 4-chlorobenzyl chloride and 1,3-dichloropropene), slight decrease (eg bisphenol A, benzo[a]pylene, carbon tetrachloride and benzene), slight increase (eg bromoform and toluene), and no effect (eg 1,1,1-trichloroethane, 1,1,2-trichloroethane and 1,2-dichloroethane). Although the decrease of GSH concentration does not reflect the cytotoxicity of chemicals, the proposed procedure utilizing isolated rat hepatpcytes seems to be useful for investigating the bioactivation of VOC, and EDC, etc. Copyright © 2001 John Wiley & Sons, Ltd. [source] 3243: In vivo quantitative measurement of oxidation repair of glutaredoxin-1ACTA OPHTHALMOLOGICA, Issue 2010PG SÖDERBERG Purpose Quantitative determination of the impact of glutaredoxin-1 on sensitivity to oxidative stress induced by in vivo exposure to ultraviolet radiation in the 300 nm wavelength region. Methods Altogether, 20 glutredoxin-1 knockout mice (Grx1 -/-) and 20 wild type C57BL/6, bred on the same background were in vivo exposed unilaterally to ultraviolet radiation in the 300 nm wavelength region (UVR-300 nm). For both the Grx1-/- and the Grx1+/+ groups, respectively, the animals were subdivided into 5 dose groups of four receiving 0.0, 2.1, 2.9, 3.6 or 4.1 kJ m^-2, depending on group belonging. At 48 hrs after exposure the animals were sacrificed, the lenses were extracted and measured for intensity of forward light scattering. The threshold dose for damage was estimated as the Maximum Tolerable Dose-2.3:16. The protection factor (PF), defined as the ratio between the threshold with protection and the threshold without protection was calculated. Results The MTD-2.3:16 was for the Grx1+/+ estimated to 3.81 kJ/m2 (95% CI, 2.82 , 6.37) and for the Grx1-/- estimated to 2.99 kJ/m2 (95% CI, 2.33 , 4.00). The PF factor for the Grx1 gene thus was 1.3. Conclusion The Grx-1 gene provides a higher tolerance to in vivo oxidative stress induced by in vivo exposure to ultraviolet radiation, allowing a 1.3 longer exposure times at the same intensity before cataract develops. [source] | ||||||||||||||||||||||||||||