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Spectral Range (spectral + range)
Kinds of Spectral Range Selected AbstractsChemInform Abstract: Photogeneration of Nitrosyl Linkage Isomers in Octahedrally Coordinated Platinum Complexes in the Red Spectral Range.CHEMINFORM, Issue 20 2010Dominik Schaniel Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Single cell manipulation, analytics, and label-free protein detection in microfluidic devices for systems nanobiologyELECTROPHORESIS, Issue 19 2005Wibke Hellmich Abstract Single cell analytics for proteomic analysis is considered a key method in the framework of systems nanobiology which allows a novel proteomics without being subjected to ensemble-averaging, cell-cycle, or cell-population effects. We are currently developing a single cell analytical method for protein fingerprinting combining a structured microfluidic device with latest optical laser technology for single cell manipulation (trapping and steering), free-solution electrophoretical protein separation, and (label-free) protein detection. In this paper we report on first results of this novel analytical device focusing on three main issues. First, single biological cells were trapped, injected, steered, and deposited by means of optical tweezers in a poly(dimethylsiloxane) microfluidic device and consecutively lysed with SDS at a predefined position. Second, separation and detection of fluorescent dyes, amino acids, and proteins were achieved with LIF detection in the visible (VIS) (488,nm) as well as in the deep UV (266,nm) spectral range for label-free, native protein detection. Minute concentrations of 100,fM injected fluorescein could be detected in the VIS and a first protein separation and label-free detection could be achieved in the UV spectral range. Third, first analytical experiments with single Sf9 insect cells (Spodoptera frugiperda) in a tailored microfluidic device exhibiting distinct electropherograms of a green fluorescent protein-construct proved the validity of the concept. Thus, the presented microfluidic concept allows novel and fascinating single cell experiments for systems nanobiology in the future. [source] MASKING INTERFERENCE AND THE EVOLUTION OF THE ACOUSTIC COMMUNICATION SYSTEM IN THE AMAZONIAN DENDROBATID FROG ALLOBATES FEMORALISEVOLUTION, Issue 9 2006Adolfo Amézquita Abstract The efficacy of communication relies on detection of species-specific signals against the background noise. Features affecting signal detection are thus expected to evolve under selective pressures represented by masking noise. Spectral partitioning between the auditory signals of co-occurring species has been interpreted as the outcome of the selective effects of masking interference. However, masking interference depends not only on signal's frequency but on receiver's range of frequency sensitivity; moreover, selection on signal frequency can be confounded by selection on body size, because these traits are often correlated. To know whether geographic variation in communication traits agrees with predictions about masking interference effects, we tested the hypothesis that variation in the male-male communication system of the Amazonian frog, Allobates femoralis, is correlated with the occurrence of a single species calling within an overlapping frequency range, Epipedobates trivittatus. We studied frogs at eight sites, four where both species co-occur and four where A. femoralis occurs but E. trivittatus does not. To study the sender component of the communication system of A. femoralis and to describe the use of the spectral range, we analyzed the signal's spectral features of all coactive species at each site. To study the receiver component, we derived frequency-response curves from playback experiments conducted on territorial males of A. femoralis under natural conditions. Most geographic variation in studied traits was correlated with either call frequency or with response frequency range. The occurrence of E. trivittatus significantly predicted narrower and asymmetric frequency-response curves in A. femoralis, without concomitant differences in the call or in body size. The number of acoustically coactive species did not significantly predict variation in any of the studied traits. Our results strongly support that the receiver but not the sender component of the communication system changed due to masking interference by a single species. [source] Tunable Guided-Mode Resonance Grating FilterADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Adriana Szeghalmi Abstract The optical characteristics of shallow 2D nanostructured polycarbonate samples are presented. Tunable guided-mode resonance filters are experimentally demonstrated for the visible spectral range when functional coatings are applied to 2D nanostructures by means of atomic layer deposition. The wavelength position of the reflection peaks can be easily tuned in a broad range (>150,nm) through rotation of the optical element around the axis normal to the substrate without changing the rest of the optical setup. Rigorous coupled wave approach simulation of model systems is performed to obtain insight into the complexity of the optical properties of these systems. The photonic nanostructures presented here are promising optics for application in ultra-compact, portable, miniaturized optical systems. [source] Engineered Light Scattering in Colloidal Photonic HeterocrystalsADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Boyang Ding Abstract Photonic heterocrystals are prepared by sandwiching films of self-assembled opal and force-assembled Langmuir,Blodgett colloidal crystals. Anomalously strong light scattering in conjunction with low reflectivity is observed with increasing angle of incidence in the spectral range of photonic bandgaps. The occurrence of light scattering at the interface has been assigned to the optical mode mismatch between the two types of photonic crystals. Photonic bandgap-related mechanisms of trapping the decaying photonic crystal modes at the interface are suggested. [source] Spectroscopic Investigation of the Europium(3+) Ion in a New ZnY4W3O16 MatrixHELVETICA CHIMICA ACTA, Issue 11 2009bieta Tomaszewicz Abstract A new Zn and Eu tungstate was characterized by spectroscopic techniques. This tungstate, of the formula ZnEu4W3O16, crystallized in the orthorhombic system and was synthesized by a solid-state reaction. It melts incongruently at 1330°. The luminescent properties, including excitation and emission processes, luminescent dynamics, and local environments of the Eu3+ ions in ZnEu4W3O16 and ZnY4W3O16,:,Eu3+ diluted phases (1, 5, and 10,mol-% of Eu3+ ion) were studied basing on the f6 -intraconfigurational transitions in the 250,720,nm spectral range. The excitation spectra of this system (,em 615 and 470,nm) show broad bands with maxima at 265 and 315,nm related to the ligand-to-metal charge-transfer (LMCT) states. The emission spectra under excitation at the O,W (265,nm) and O,Eu3+ (315,nm) LMCT states present the blue-green emission bands. The emission of tungstate groups mainly originate from the charge-transfer state of excited 2p orbitals of O2, to the empty orbitals of the central W6+ ions. On the other hand, in the emission of the Eu3+ ions, both the charge transfer from O2, to Eu3+ and the energy transfer from W6+ ions to Eu3+ are involved. The emission spectra under excitation at the 7F0,5L6 transition of the Eu3+ ion (394,nm) of ZnY4W3O16,:,Eu3+ diluted samples show narrow emission lines from the 5D3, 5D2, and 5D1 emitting states. The effect of the active-ion (Eu3+) concentration on the colorimetric characteristic of the emissions of the compound under investigation are presented. [source] Photonic Crystal Formed by the Imaginary Part of the Refractive IndexADVANCED MATERIALS, Issue 24 2010Juntao Li A periodic array of dye-doped disks that form a 2D photonic lattice is fabricated and characterized. The array was generated by interference lithography, and the voids of the template were filled by SU8 without doping. This creates a photonic lattice with a uniform real part of the refractive index, but a periodically modulated imaginary part. The structure is characterized by diffraction measurements; the structure only diffracts light in the spectral range where the dye absorbs, hence acts like a truly imaginary index photonic crystal. [source] Two-Photon Absorption-Related Properties of Functionalized BODIPY Dyes in the Infrared Range up to Telecommunication WavelengthsADVANCED MATERIALS, Issue 10-11 2009Pierre-Antoine Bouit Aza boron-dipyrromethene dyes functionalized by extended donor-,-conjugated moieties present high potentialities for nonlinear applications in the telecommunication spectral range (1300,1500,nm). Their significant two-photon absorption cross-sections (,2,>,600 GM) over this entire spectral range, combined with their high stability and solubility, allow nonlinear transmission experiments. [source] Cover Picture: J. Biophoton.JOURNAL OF BIOPHOTONICS, Issue 6 20086/200 Mouse muscle fibres (gastrocnemius muscle) 3D reconstruction. Infrared excitation at 800 nm. Nuclei are labelled with Hoechst33342 (red) and acquired in the epi-channel in the spectral range 440,480 nm. SHG (green) from myosin fibres is acquired in transmission channel. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Particle surface temperature measurements with multicolor band pyrometryAICHE JOURNAL, Issue 1 2009Hong Lu Abstract A noncontact, color-band pyrometer, based on widely available, inexpensive digital imaging devices, such as commercial color cameras, and capable of pixel-by-pixel resolution of particle-surface temperature and emissivity is demonstrated and described. This diagnostic instrument is ideally suited to many combustion environments. The devices used in this method include color charge-coupled device (CCD), or complementary metal oxide semiconductor (CMOS) digital camera, or any other color-rendering camera. The color camera provides spectrally resolved light intensity data of the image, most commonly for three color bands (Red, Green, and Blue,), but in some cases for four or more bands or for a different set of colors. The CCD or CMOS sensor-mask combination has a specific spectral response curve for each of these color bands that spans the visible and often near infrared spectral range. A theory is developed, based on radiative heat transfer and camera responsivity that allows quantitative surface temperature distribution calculation, based on a photograph of an object in emitted light. Particle surface temperature calculation is corrected by heat transfer analysis with reflection between the particle and reactor wall for particles located in furnace environments, but such corrections lead to useful results only when the particle temperature is near or below the wall temperatures. Wood particle-surface temperatures were measured with this color-band pyrometry during pyrolysis and combustion processes, which agree well with thermocouple measured data. Particle-surface temperature data simultaneously measured from three orthogonal directions were also mapped onto the surface of a computer generated 3-D (three-dimensional) particle model. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] Future possibilities of the Linac Coherent Light SourceJOURNAL OF SYNCHROTRON RADIATION, Issue 3 2004M. Cornacchia A study of the potential for the development of the Linac Coherent Light Source (LCLS) beyond the specifications of the baseline design is presented. These future developments include delivery of X-ray pulses in the 1,fs regime, extension of the spectral range, increase of the FEL power, exploitation of the spontaneous emission, and a more flexible time structure. As this potential is exploited, the LCLS can maintain its role as a world-leading instrument for many years beyond its commissioning in 2008 and initial operation as the world's first X-ray free-electron laser. [source] Center for Synchrotron Biosciences' U2B beamline: an international resource for biological infrared spectroscopyJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2002N. S. Marinkovic A synchrotron infrared (IR) beamline, U2B, dedicated to the biomedical and biological sciences has been constructed and is in operation at the National Synchrotron Light Source (NSLS) of Brookhaven National Laboratory. The facility is operated by the Center for Synchrotron Biosciences of the Albert Einstein College of Medicine in cooperation with the NSLS. Owing to the broadband nature of the synchrotron beam with brightness 1000 times that of conventional sources, Fourier transform IR spectroscopy experiments are feasible on diffraction-limited sample areas at high signal-to-noise ratios and with relatively short data-acquisition times. A number of synchrotron IR microscopy experiments that have been performed in the mid-IR spectral range (500,5000,cm,1) are summarized, including time-resolved protein-folding studies in the microsecond time regime, IR imaging of neurons, bone and other biological tissues, as well as imaging of samples of interest in the chemical and environmental sciences. Owing to the high flux output of this beamline in the far-IR region (50,500,cm,1), investigations of hydrogen bonding and dynamic molecular motions of biomolecules have been carried out from 10 to 300,K using a custom-made cryostat and an evacuated box. This facility is intended as an international resource for biological IR spectroscopy fully available to outside users based on competitive proposal. [source] Characterization of the respiration of 3T3 cells by laser-induced fluorescence during a cyclic heating processLASER PHYSICS LETTERS, Issue 4 2010J. Beuthan Abstract The use of lasers in the near infrared spectral range for laser-induced tumor therapy (LITT) demands a new understanding of the thermal responses to repetitive heat stress. The analysis of laser-induced fluorescence during vital monitoring offers an excellent opportunity to solve many of the related issues in this field. The laser-induced fluorescence of the cellular coenzyme NADH was investigated for its time and intensity behavior under heat stress conditions. Heat was applied to vital 3T3 cells (from 22 °C to 50 °C) according to a typical therapeutical time regime. A sharp increase in temperature resulted in non-linear time behavior when the concentration of this vital coenzyme changed. There are indications that biological systems have a delayed reaction on a cellular level. These results are therefore important for further dosimetric investigations. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] SPIDER: A decade of measuring ultrashort pulsesLASER PHYSICS LETTERS, Issue 4 2008M.E. Anderson Abstract It was ten years ago in Rochester, New York that the first SPIDER was built. This simple acronym belies the subtleties of its inner workings; Spectral Phase Interferometry for Direct Electric-field Reconstruction (the "f" in field conveniently missed the cut) is a device that measures ultrashort pulses, utilizing spectral shearing interferometry and directly recovering the spectral phase. The very first SPIDER apparatus occupied nearly half an optical table, used a scanning monochromator, and had no computerized inversion routine. In the intervening decade, SPIDER has grown up. It has found a strong foothold in ultrafast laboratories throughout the world. Multiple groups have found useful new applications with this vital measurement tool, while others have contributed to the improvement of SPIDER itself, reaching to ever shorter pulses, new wavelength regimes, and making devices more sensitive, robust, smaller and faster. It also adapts to a field of research that changes rapidly. It was first designed to track and quantify the remaining spectral phase in a pulse to perfect its compression. In ten years, with the advent of pulse shapers, the real benefits of field diagnostics are becoming apparent. We have shifted away from the race towards the shortest IR pulse to a wide use of complex shaped pulses in almost every spectral range from far IR to XUV. But the quest of the shortest pulse is not over and new compression techniques utilize really broad spectra that are highly structured. All these applications provide new challenges for characterization techniques. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] New data on investigation of novel laser ceramic on the base of cubic scandium sesquioxide: two-band tunable CW generation of Yb3+:Sc2O3 with laser-diode pumping and the dispersion of refractive index in the visible and near-IR of undoped Sc2O3LASER PHYSICS LETTERS, Issue 7 2007K. Takaichi Abstract We report on the first achievement of tunable twoband "one-micron" CW oscillation in the 2F5/2 , 2F7/2 channel of Yb3+ activator ions in Sc2O3 ceramics with CW laserdiode pumping, as well as on results of precise measurement of the refractive index and its dispersion in spectral range 0.365 , 2.325 ,m and full transmission spectra of undoped Sc2O3 ceramics fabricated by the VSN method. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Efficient broadband optical parametric amplification of supercontinuum in visible by narrowband pumpLASER PHYSICS LETTERS, Issue 5 2007D. V. Khakhulin Abstract It is shown that application of narrowband pump for non-collinear parametric amplification of supercontinuum radiation is more profitable than of broadband one. The usage of 0.5 nm bandwidth pump with energy of 350 ,J allowed us to get 20 percents signal-to-pump efficiency during amplification of supercontinuum radiation belonging to a spectral range between 550 and 750 nm. (© 2007 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Stimulated Raman scattering in mid IR spectral range 2.31,2.75,3.7 µm in BaWO4 crystal under 1.9 and 1.56 µm pumpingLASER PHYSICS LETTERS, Issue 1 2006T.T. Basiev Abstract Stimulated Raman scattering (SRS) in newly developed BaWO4 crystal was investigated. Under 1.9 µm pumping one Stokes component and under 1.56 µm pumping several (up to four) Stokes components were observed. SRS and laser breakdown thresholds were measured. For the first time 2.75 µm and 3.7 µm radiation was obtained using crystalline Raman shifter. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Multimode fiber lasers based on Bragg gratings and double-clad Yb-doped fibersLASER PHYSICS LETTERS, Issue 9 2004A. S. Kurkov Abstract We have realized a set of multimode lasers based on a double-clad Yb-doped fiber and Bragg gratings written on a graded-index multimode fiber. Efficient laser operation in the spectral range of 1.03-1.09 ,m has been observed. Spectral characteristics of the laser emission have been investigated. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Delineating melanoma using multimodal polarized light imagingLASERS IN SURGERY AND MEDICINE, Issue 1 2009Zeina Tannous Abstract Background and Significance Melanoma accounts for 3% of all skin cancers but causes 83% of skin cancer deaths. The first step in treatment of melanoma is the removal of the lesions, usually by surgical excision. Currently most lesions are removed without intraoperative margin control. Post-operative methods inspect 1,2% of the surgical margin and are prone to sampling errors. In this study we evaluate the use of reflectance and fluorescence polarization imaging for the demarcation of melanoma in thick fresh skin excisions. Materials and Methods Pigmented lesions clinically suspicious for melanoma were elliptically excised with proper margins. Elliptical surgical excisions were vertically bisected along the short axis of the specimen into two halves in the middle of the pigmented lesions. The vertically bisected tumor face was imaged. After that, one half of the sample was briefly stained in aqueous 2 mg/ml solution of tetracycline, whereas another half was stained in 0.2 mg/ml aqueous solution of methylene blue. Then both specimens were reimaged. Reflectance images were acquired in the spectral range between 390 and 750 nm. Fluorescence images of the tetracycline-stained tissue were excited at 390 nm and registered between 450 and 700 nm. Fluorescence of the methylene blue-stained samples was excited at 630 nm and registered between 650 and 750 nm. After imaging, the tissue was processed for standard H&E histopathology. The resulting histological and optical images were compared to each other. Results and Conclusions Our findings demonstrate that both tetracycline and methylene blue are suitable for imaging dysplastic and benign nevi. Melanoma is better delineated in the samples stained in methylene blue. Accurate and rapid delineation of melanoma in standard fresh surgical excisions appears feasible. Lasers Surg. Med. 41:10,16, 2009. © 2008 Wiley-Liss, Inc. [source] Glowworms: a review of Arachnocampa spp. and kinLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2007V. B. Meyer-Rochow Abstract The term ,glowworm' is used in connection with the flightless females of lampyrid fireflies and to describe the luminescent larvae of certain fungus gnats that belong to the subfamilies Arachnocampinae, Keroplatinae and Macrocerinae of the dipteran family Keroplatidae. This review focuses on the luminescent larval fungus gnats. The weakly luminescent species of the Holarctic feed mainly on fungal spores, but some, such as Orfelia fultoni, have turned to a carnivorous diet. Larval Australian and New Zealand Arachnocampa spp. produce brighter in vivo (but not necessarily in vitro) lights, live in cool, damp and dark places and are exclusively predatory. They lure their prey (usually small flying insects) with the help of their blue-green light emissions towards snares consisting of vertical silk threads coated with sticky mucus droplets. Fungus gnats with similar ,fishing lines' are found in the Neotropics, but they are not luminescent. The larval stage is longest in the life cycle of Arachnocampa, lasting up to a year, depending on climatic conditions such as temperature and humidity as well as food supply. In A. luminosa, but not the Australian A. flava, female pupae and even female imagines are luminescent. However, it remains to be demonstrated whether it is the light of the female, a pheromone or both that attract the males. Light organs and the chemical reactions to produce light differ between the holarctic and the Australian/New Zealand species. Prey is attracted only by the glowworm's light; odours of the fishing lines or the glowworms themselves are not involved. Recognition of the prey by the glowworm involves mechano- and chemoreception. The eyes of both larval and adult glowworms are large and functional over a spectral range covering UV to green wavelengths. Adults are poor fliers, live only for a few days, have degenerate mouth parts and do not feed. Maintenance of glowworms in captivity is possible and the impact of tourism on glowworms in natural settings can be minimized through appropriate precautions. Copyright © 2007 John Wiley & Sons, Ltd. [source] A simple device for the evaluation of the UV radiation indexMETEOROLOGICAL APPLICATIONS, Issue 2 2003Giuseppe Rocco Casale The solar ultraviolet radiation (UV) flux density at the earth's surface depends on the incoming solar energy and the transmission properties of the atmosphere. UV radiation is strongly absorbed by ozone in the spectral range 200,310 nm, while the attenuation is increasingly weaker at longer wavelengths. Following the discovery of the Antarctic ozone hole in 1985, the risk of a possible UV increase at ground level, due to the observed stratospheric ozone depletion, has heightened the interest within the scientific community given the potentially harmful effects on terrestrial and aquatic ecosystems. Spectroradiometers, broad-band meters and dosimeters may be used for measurements of solar UV. In addition, radiation transfer models can be used to quantify UV irradiances at various times and locations, provided that the extraterrestrial solar radiation and the state of the atmosphere are known. Information about UV radiation at the earth's surface is given by the ultraviolet index ,UVI', which is defined as the effective integrated irradiance (280,400 nm) weighted by the erythemal action spectrum. The UV Index is widely used by many international weather services as an indicator of UV levels at the earth's surface providing public awareness of the effects of prolonged exposure to the sun's rays. The aim of this paper is to present a device capable of estimating the UV Index. This device is a compact disc, used as a sundial, and is based on modelled UV irradiances derived from the STAR radiative transfer model (System for Transfer of Atmospheric Radiation). The device was tested in an urban setting under clear sky conditions. Copyright © 2003 Royal Meteorological Society [source] Probing the origin of the dark material on IapetusMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2010F. Tosi ABSTRACT Among the icy satellites of Saturn, Iapetus shows a striking dichotomy between its leading and trailing hemispheres, the former being significantly darker than the latter. Thanks to the Visual and Infrared Mapping Spectrometer (VIMS) imaging spectrometer on-board Cassini, it is now possible to investigate the spectral features of the satellites in Saturn system within a wider spectral range and with an enhanced accuracy than with previously available data. In this work, we present an application of the G-mode method to the high resolution, visible and near-infrared data of Phoebe, Iapetus and Hyperion collected by Cassini/VIMS, in order to search for compositional correlations. We also present the results of a dynamical study on the efficiency of Iapetus in capturing dust grains travelling inwards in Saturn system with the aim of evaluating the viability of the Poynting,Robertson drag as the physical mechanism transferring the dark material to the satellite. The results of spectroscopic classification are used jointly with the ones of the dynamical study to describe a plausible physical scenario for the origin of Iapetus' dichotomy. Our work shows that mass transfer from the outer Saturnian system is an efficient mechanism, particularly for the range of sizes hypothesized for the particles composing the newly discovered outer ring around Saturn. Both spectral and dynamical data indicate Phoebe as the main source of the dark material. However, due to considerations on the collisional history of the Saturnian irregular satellites and to the differences in the spectral features of Phoebe and the dark material on Iapetus in the visible and ultraviolet range, we suggest a multisource scenario where now extinct prograde satellites and the disruptive impacts that generated the putative collisional families played a significant role in supplying the original amount of dark material. [source] Effect of Two Different UVA Doses on the Rabbit Cornea and LensPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2009ejka, estmír The aim of the present paper was to examine the irradiation effect of two doses of UVA rays (365 nm) on the rabbit cornea and lens. Corneas of anesthetized adult albino rabbits were irradiated with UVA rays for 5 days (daily dose 1.01 J cm,2 in one group of rabbits and daily dose 2.02 J cm,2 in the second group of animals). The third day after the last irradiation, the rabbits were killed, and their eyes were employed for spectrophotometrical, biochemical and immunohistochemical investigations. Normal eyes served as controls. Absorption spectra of the whole corneal centers were recorded over the UV,VIS (visible) spectral range. Levels of antioxidant and prooxidant enzymes, nitric oxide synthases and nitric oxide (indirectly measured as nitrate concentration) were investigated in the cornea. Malondialdehyde, a byproduct of lipid peroxidation, was examined in the cornea and lens. The results show that the staining for endothelial nitric oxide synthase was more pronounced in corneas irradiated with the higher UVA dose. Otherwise, UVA rays at either dose did not significantly change corneal light absorption properties and did not cause statistically significant metabolic changes in the cornea or lens. In conclusion, UVA rays at the employed doses did not evoke harmful effects in the cornea or lens. [source] Absorption Spectra of Human Skin In Vivo in the Ultraviolet Wavelength Range Measured by OptoacousticsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2009Merve Meinhardt Knowledge of the optical properties of human skin in the ultraviolet range is fundamental for photobiologic research. However, optical properties of human skin in the ultraviolet spectral range have so far mainly been measured ex vivo. We have determined the absorption spectra of human skin in vivo in the wavelength range from 290 to 341 nm in 3 nm steps using laser optoacoustics. In this technique, optical properties are derived from the pressure profile generated by absorbed light energy in the sample. In a study on 20 subjects belonging to phototypes I,IV, we studied the optical properties at the volar and dorsal aspect of the forearm as well as on the thenar. Analysis of the measured absorption spectra shows that comparable skin areas,like different sides of the forearm,have qualitatively similar optical characteristics. Still, the optical properties may vary substantially within the same area, probably due to the skin structure and inhomogeneities. Comparison of the spectra from different skin sites indicates that the spectral characteristics of the stratum corneum and its chromophores play an important role for the optical properties of human skin in vivo in the ultraviolet B range. [source] Highly conductive and optically transparent GZO films grown under metal-rich conditions by plasma assisted MBEPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 3-4 2010H. Y. Liu Abstract We demonstrate a critical effect of a metal-to-oxygen ratio on the electrical, optical, and structural properties of ZnO films heavily doped with Ga (carrier concentration in the range of 1020,1021 cm,3) grown by plasma-assisted molecular beam epitaxy. The as-grown layers prepared under the metal-rich conditions exhibited resistivities below 3 × 10,4 , cm and an optical transparency exceeding 90% in the visible spectral range as well as a large blue shift of the transmission/absorption edge attributed to the Burstein,Moss shift of the Fermi level deep into the conduction band, indicating high donor concentration. In contrast, the films grown under the oxygen-rich conditions required thermal activation and showed inferior properties. Furthermore, electrical measurements point to the nonuniform depth distribution of free carriers. An oxygen-pressure-dependent surface disordering is suggested to be responsible for the drastic effect of the metal-to-oxygen ratio on the film properties. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical anisotropy of A - and M -plane InN grown on free-standing GaN substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2010P. Schley Abstract Wurtzite A - and M -plane InN films were grown by molecular beam epitaxy (MBE) on free-standing GaN substrates. Spectroscopic ellipsometry (SE) in the photon energy range from 0.56 up to 15,eV was applied in order to determine the ordinary and extraordinary complex dielectric function (DF) of InN. A distinct optical anisotropy was found over the whole energy range. The extraordinary absorption edge in comparison to the ordinary one is shifted to higher energies confirming previous studies. The investigations in the upper vacuum-ultraviolet (VUV) spectral range (9.5,15,eV) yielded transition energies for four critical points (CPs) of the band structure (BS) which have not been observed so far. [source] UV emission on a Si substrate: Optical and structural properties of ,-CuCl on Si grown using liquid phase epitaxy techniquesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2009A. Cowley Abstract Considerable research is being carried out in the area of wide band gap semiconductor materials for light emission in the 300,400 nm spectral range. Current materials being used for such devices are typically based on II,VI and III-nitride compounds and variants thereof. However, one of the major obstacles to the successful fabrication of III-N devices is lattice mismatch-induced high dislocation densities for epitaxially grown layers on non-native substrates. ,-CuCl is a direct bandgap material and an ionic wide bandgap I,VII semiconductor with a room temperature free exciton binding energy of ,190 meV (compared to ,25 meV and ,60 meV for GaN and ZnO, respectively) and has a band gap of 3.4 eV (, , 366 nm). The lattice constant of ,-CuCl (0.541 nm) is closely matched to that of Si (0.543 nm). This could, in principle, lead to the development of optoelectronic systems based on CuCl grown on Si. Research towards this end has successfully yielded polycrystalline ,-CuCl on Si(100) and Si(111) using vacuum-based deposition techniques [1]. We report on developments towards achieving single crystal growth of CuCl from solution via Liquid Phase Epitaxy (LPE) based techniques. Work is being carried out using alkali halide flux compounds to depress the liquidus temperature of the CuCl below its solid phase wurtzite-zincblende transition temperature (407 °C [2]) for solution based epitaxy on Si substrates. Initial results show that the resulting KCl flux-driven deposition of CuCl onto the Si substrate has yielded superior photoluminescence (PL) and X-ray excited optical luminescence (XEOL) behavior relative to comparitively observed spectra for GaN or polycrystalline CuCl. This enhancement is believed to be caused by an interaction between the KCl and CuCl material subsequent to the deposition process, perhaps involving a reduction in Cl vacancy distributions in CuCl. This paper presents a detailed discussion of a CuCl LPE growth system as well as the characterization of deposited materials using X-ray diffraction (XRD), room temperature and low temperature PL, and XEOL. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] All-organic optocouplers based on polymer light-emitting diodes and photodetectorsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2008N. A. Stathopoulos Abstract In this work, we demonstrate all organic flexible polymeric optocouplers by utilizing a donor-acceptor bulk heterojunction polymer photodetector (PD) as the output unit and a polymer light-emitting diode (PLED) as the input unit. The input unit is a single-layer PLED on a glass or a plastic (PET) substrate utilizing a green emitting polyfluorene-benzothiadiazole copolymer in the active layer. The output unit is a single-layer PD on a glass substrate utilizing a P3HT:PCBM(1:1 by weight) blend, where P3HT is regioregular poly(3-hexylthiophene) and PCBM is (6,6)-phenyl-C61 -butyric acid methyl ester. The electroluminescence spectrum of the PLED peaks at 530 nm and covers a spectral range that coincides quite well with the PD absorption spectrum (between 450 and 650 nm). The current density transfer ratio reaches 0.012% for an optocoupler that operates at 0 V and 15 V for the PD and PLED, respectively. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Chemical bath deposition of CdSe and CdS nanocrystalline films: tailoring of morphology, optical properties and carrier dynamicsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2008Abstract We review the results of our research towards tailoring morphology and optical properties of films consisting of closely-spaced nanocrystals of CdSe and CdS whose optical band-gap can be tuned to cover the whole visible spectral range. On basis of the obtained results, in particular of photoexcited carrier dynamics, we have proposed a microscopic model that describes well the optical properties of the films. We have also showed that the spin relaxation of electrons in these nanocrystalline films is different than that in mutually isolated nanocrystals of the same size. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Changes in optical properties of MnAs thin films on GaAs(001) induced by ,- to ,-phase transitionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2008B. Gallas Abstract MnAs layers with 45 nm thickness were grown epitaxially on GaAs(001) substrates. Ellipsometry measurements were made in the spectral range 0.045 eV to 6 eV as a function of temperature (between ,10 °C and 50 °C) at 70° of incidence. In this way the transition from the hexagonal ,-phase to the orthorhombic ,-phase could be monitored. Non-zero off-diagonal elements of the Jones matrix for an azimuth of 38° off the [10] axis of the substrate indicate that the optical functions of MnAs are anisotropic in both phases. The optical conductivity exhibits low-energy interband transitions around 0.3 eV, more clearly seen in the ,-phase than in the ,-phase. Extrapolation of the optical conductivity to zero frequency confirms that the ,-phase is about two times more conducting than the ,-phase. A broad structure is observed in the visible range around 3 eV. The ,-phase is characterised by an anisotropy induced energy difference of this structure with a maximum at 2.8 eV for the extraordinary index and at 3.15 eV for the ordinary index. This difference vanishes in the ,-phase in which anisotropy mainly induces changes in amplitude of the 3 eV structure. The assignment of the structures will be discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||||||||||||||