Zeitschriftenartikel: „Infra-Red Band“

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Sudhakar Reddy, B., K. Vemasevana Raju, S. Sailaja, C. Nageswara Raju und D. Sreekantha Reddy. „NIR Emission Analysis of Er³⁺/Yb³⁺ and Er³⁺/ Tm³⁺ Ions Doped Zinc lithium Boro Tellurite (ZLiBT) Glasses for Optical Fiber Amplification“. Advanced Materials Research 123-125 (August 2010): 19–22. http://dx.doi.org/10.4028/www.scientific.net/amr.123-125.19.

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This paper reports on the development and the near infra-red emission(NIR) analysis of Er3+/Yb3+ and Er3+/ Tm3+ ions doped TeO2 - B2O3 – ZnO - Li2O glasses for tunable laser and optical fiber amplification. From the measured near infra-red emission spectra of Er3+/Yb3+, Er3+/Tm3+: ZLiBT glasses have revealed the prominent near infra-red emission bands at 1532 nm (4I13/2 → 4I15/2), with an excitation wavelength of λexci = 515 nm (Ar+ ion laser). The full width at half-maxima (FWHM) values are also estimated from the measured near infra-red emission spectra of the glasses. Based on spectral results, broad near infra-red emissions should have potential applications in broadly tunable laser sources and broad band optical amplification at low-loss telecommunication windows.

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Zhao, Liang, Jixue Liu, Stefan Peters, Jiuyong Li, Simon Oliver und Norman Mueller. „Investigating the Impact of Using IR Bands on Early Fire Smoke Detection from Landsat Imagery with a Lightweight CNN Model“. Remote Sensing 14, Nr. 13 (25.06.2022): 3047. http://dx.doi.org/10.3390/rs14133047.

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Smoke plumes are the first things seen from space when wildfires occur. Thus, fire smoke detection is important for early fire detection. Deep Learning (DL) models have been used to detect fire smoke in satellite imagery for fire detection. However, previous DL-based research only considered lower spatial resolution sensors (e.g., Moderate-Resolution Imaging Spectroradiometer (MODIS)) and only used the visible (i.e., red, green, blue (RGB)) bands. To contribute towards solutions for early fire smoke detection, we constructed a six-band imagery dataset from Landsat 5 Thematic Mapper (TM) and Landsat 8 Operational Land Imager (OLI) with a 30-metre spatial resolution. The dataset consists of 1836 images in three classes, namely “Smoke”, “Clear”, and “Other_aerosol”. To prepare for potential on-board-of-small-satellite detection, we designed a lightweight Convolutional Neural Network (CNN) model named “Variant Input Bands for Smoke Detection (VIB_SD)”, which achieved competitive accuracy with the state-of-the-art model SAFA, with less than 2% of its number of parameters. We further investigated the impact of using additional Infra-Red (IR) bands on the accuracy of fire smoke detection with VIB_SD by training it with five different band combinations. The results demonstrated that adding the Near-Infra-Red (NIR) band improved prediction accuracy compared with only using the visible bands. Adding both Short-Wave Infra-Red (SWIR) bands can further improve the model performance compared with adding only one SWIR band. The case study showed that the model trained with multispectral bands could effectively detect fire smoke mixed with cloud over small geographic extents.

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Merlin Mathew, Rincy, S. Purushothaman und P. Rajeswari. „Performance comparisons of particle swarm optimization, echo state neural network and genetic algorithm for vegetation segmentation“. International Journal of Engineering & Technology 7, Nr. 1.1 (21.12.2017): 184. http://dx.doi.org/10.14419/ijet.v7i1.1.9286.

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This article presents the implementation of vegetation segmentation by using soft computing methods: particle swarm optimization (PSO), echostate neural network(ESNN) and genetic algorithm (GA). Multispectral image with the required band from Landsat 8 (5, 4, 3) and Landsat 7 (4, 3, 2) are used. In this paper, images from ERDAS format acquired by Landsat 7 ‘Paris.lan’ (band 4, band 3, Band 2) and image acquired from Landsat 8 (band5, band 4, band 3) are used. The soft computing algorithms are used to segment the plane-1(Near infra-red spectra) and plane 2(RED spectra). The monochrome of the two segmented images is compared to present performance comparisons of the implemented algorithms.

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He Guangzong, 何光宗, 熊长新 Xiong Changxin, 李钱陶 Li Qiantao und 吴小丽 Wu Xiaoli. „Dual Band Infra-Red Protective Coatings on Germanium Substrate“. Acta Optica Sinica 31, s1 (2011): s100105. http://dx.doi.org/10.3788/aos201131.s100105.

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Rathborne, J. M., und M. G. Burton. „Results from the South Pole Infra-Red EXplorer Telescope“. Highlights of Astronomy 13 (2005): 937–44. http://dx.doi.org/10.1017/s153929960001769x.

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AbstractThe SPIREX telescope, located at the Amundsen-Scott South Pole Station, was a prototype system developed to exploit the excellent conditions for IR observing at the South Pole. Observations over two winter seasons achieved remarkably deep, high-resolution, wide-field images in the 3-5 μm wavelength regime. Several star forming complexes were observed, including NGC 6334, Chamaeleon I, η Chamaeleontis, the Carina Nebula, 30 Doradus, RCW 57, RCW 38, as well as the Galactic Center. Images were obtained of lines at 2.42/μm H2, 3.29/μm PAH and 4.05/μm Br α, as well as 3.5/μm L-band and 4.7 μm M-band continuum emission. These data, combined with near-IR, mid-IR, and radio continuum maps, reveal the environments of these star forming sites, as well as any protostars lying within them. The SPIREX project, its observing and reduction methods, and some sample data are summarized here.

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Gossn, Juan, Kevin Ruddick und Ana Dogliotti. „Atmospheric Correction of OLCI Imagery over Extremely Turbid Waters Based on the Red, NIR and 1016 nm Bands and a New Baseline Residual Technique“. Remote Sensing 11, Nr. 3 (22.01.2019): 220. http://dx.doi.org/10.3390/rs11030220.

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A common approach to the pixel-by-pixel atmospheric correction of satellite water colour imagery is to calculate aerosol and water reflectance at two spectral bands, typically in the near infra-red (NIR, 700–1000 nm) or the short-wave-infra-red (SWIR, 1000–3000 nm), and then extrapolate aerosol reflectance to shorter wavelengths. For clear waters, this can be achieved simply for NIR bands, where the water reflectance can be assumed negligible i.e., the “black water” assumption. For moderately turbid waters, either the NIR water reflectance, which is non-negligible, must be modelled or longer wavelength SWIR bands, with negligible water reflectance, must be used. For extremely turbid waters, modelling of non-zero NIR water reflectance becomes uncertain because the spectral slopes of water and aerosol reflectance in the NIR become similar, making it difficult to distinguish between them. In such waters the use of SWIR bands is definitely preferred and the use of the MODIS bands at 1240 nm and 2130 nm is clearly established although, on many sensors such as the Ocean and Land Colour Instrument (OLCI), such SWIR bands are not included. Instead, a new, cheaper SWIR band at 1016 nm is available on OLCI with potential for much better atmospheric correction over extremely turbid waters. That potential is tested here. In this work, we demonstrate that for spectrally-close band triplets (such as OLCI bands at 779–865–1016 nm), the Rayleigh-corrected reflectance of the triplet’s “middle” band after baseline subtraction (or baseline residual, BLR) is essentially independent of the atmospheric conditions. We use the three BLRs defined by three consecutive band triplets of the group of bands 620–709–779–865–1016 nm to calculate water reflectance and hence aerosol reflectance at these wavelengths. Comparison with standard atmospheric correction algorithms shows similar performance in moderately turbid and clear waters and a considerable improvement in extremely turbid waters.

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Unavane, M., und G. Gilmore. „2.6. Resolved near-IR survey of the inner Galaxy“. Symposium - International Astronomical Union 184 (1998): 69–70. http://dx.doi.org/10.1017/s0074180900084059.

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The analysis of resolved DENIS (Deep Near Infra Red Survey of the Southern Sky) I,J and K band data shows good evidence (≳ 3σ) in the J and K band number counts to support the existence of a kiloparsec-scale bar with its major axis in the first quadrant. A star by star dereddening of this K data combined with supplementary nbL band data (3.6μm) gives number count contrasts consistent with low angle (≲ 20 degrees) bar models in the literature.

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Lee, Heesu, Seungjin Hwang, Sungyoon Lee, Kyung Hee Hong, Hyeon-Myeong Oh, Young-Jo Park, Ha-Neul Kim und Tae Jun Yu. „Measurement of Nd:Y2O3 broad band near infra-red transmittance using FTIR system“. Optical Materials 143 (September 2023): 114227. http://dx.doi.org/10.1016/j.optmat.2023.114227.

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9

Dr. S.Varadarajan, A. Rajani,. „Estimation and Validation of Land Surface Temperature by using Remote Sensing & GIS for Chittoor District, Andhra Pradesh“. Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, Nr. 5 (11.04.2021): 607–17. http://dx.doi.org/10.17762/turcomat.v12i5.1059.

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Land Surface Temperature (LST) quantification is needed in various applications like temporal analysis, identification of global warming, land use or land cover, water management, soil moisture estimation and natural disasters. The objective of this study is estimation as well as validation of temperature data at 14 Automatic Weather Stations (AWS) in Chittoor District of Andhra Pradesh with LST extracted by using remote sensing as well as Geographic Information System (GIS). Satellite data considered for estimation purpose is LANDSAT 8. Sensor data used for assessment of LST are OLI (Operational Land Imager) and TIR (Thermal Infrared). Thermal band contains spectral bands of 10 and 11 were considered for evaluating LST independently by using algorithm called Mono Window Algorithm (MWA). Land Surface Emissivity (LSE) is the vital parameter for calculating LST. The LSE estimation requires NDVI (Normalized Difference Vegetation Index) which is computed by using Band 4 (visible Red band) and band 5 (Near-Infra Red band) spectral radiance bands. Thermal band images having wavelength 11.2 µm and 12.5 µm of 30th May, 2015 and 21st October, 2015 were processed for the analysis of LST. Later on validation of estimated LST through in-suite temperature data obtained from 14 AWS stations in Chittoor district was carried out. The end results showed that, the LST retrieved by using proposed method achieved 5 per cent greater correlation coefficient (r) compared to LST retrieved by using existing method which is based on band 10.

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Ilehag, R., M. Weinmann, A. Schenk, S. Keller, B. Jutzi und S. Hinz. „REVISITING EXISTING CLASSIFICATION APPROACHES FOR BUILDING MATERIALS BASED ON HYPERSPECTRAL DATA“. ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W3 (19.10.2017): 65–71. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w3-65-2017.

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Classification of materials found in urban areas using remote sensing, in particular with hyperspectral data, has in recent times increased in importance. This study is conducting classification of materials found on building using hyperspectral data, by using an existing spectral library and collected data acquired with a spectrometer. Two commonly used classification algorithms, Support Vector Machine and Random Forest, were used to classify the materials. In addition, dimensionality reduction and band selection were performed to determine if selected parts of the full spectral domain, such as the Short Wave Infra-Red domain, are sufficient to classify the different materials. We achieved the best classification results for the two datasets using dimensionality reduction based on a Principal Component Analysis in combination with a Random Forest classification. Classification using the full domain achieved the best results, followed by the Short Wave Infra-Red domain.

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Dowdeswell, J. A. „Comparison of Landsat Multispectral Scanner and Thematic Mapper Radiometric and Spatial Characteristics Over Glaciers (Abstract)“. Annals of Glaciology 9 (1987): 245. http://dx.doi.org/10.3189/s0260305500000835.

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For more than 10 years, images obtained from the four Landsat Multispectral Scanner (MSS) bands have provided important data for mapping and glaciological studies in the inaccessible polar regions. During this period, the specifications of the MSS have remained little altered, to allow data comparability. More recently, satellites 4 and 5 of the Landsat series have been equipped additionally with Thematic Mapper (TM) sensors. The TM has 7 bands in the visible, near infra-red, mid infra-red, and thermal infra-red, together with a larger dynamic range and improved spatial resolution relative to the MSS. The aim of this paper is to compare MSS and TM computer-compatible tapes (CCTs) from a glacierized area in order to demonstrate the advantages of using TM data in glaciological applications.The digital MSS and TM scenes compared were imaged simultaneously from Landsat 5 on 5 May 1984 over the north-west part of Spitsbergen, Svalbard (path 218, row 3). This location was selected because of the range of glaciological features present: numerous valley glaciers, the ice field of Holtedahlfonna, fast ice, and ice floes. Partially cloud-covered imagery was preferred, to allow comparison of the two sensors in terms of their ability to distinguish between clouds and snow. The time of year is also advantageous, in that Sun elevation (27°) is high enough for detector saturation to occur in MSS band 2 (Dowdeswell and McIntyre 1986). Surface-elevation data from airborne radio echo-sounding, and other ancilliary glaciological information, are also available for this part of Svalbard.Differences in the dynamic range and the wavelengths over which TM and MSS data are collected have two main implications for glaciological studies. First, snow and snow-covered ice masses can be distinguished easily from cloud cover in TM band 5 (1.57 to 1.78 μm). Snow appears dark whereas clouds are light at this wavelength. For example, thin clouds over part of Oscar II Land in Spitsbergen became apparent. In many MSS scenes of the Antarctic, the cloud-free ice-sheet surface has been misidentified as cloud-covered during quality-control analysis. Secondly, the wider dynamic range of the TM sensors means that saturation occurs less frequently over snow than was the case with MSS imagery. Digital analysis of MSS and TM scene radiance over Spitsbergen demonstrates this fact and implies that ice-surface topographic information will only rarely be degraded in TM imagery, although TM band 1 (0.45 to 0.52 μm) is most often saturated.The nominal spatial resolution of TM sensors is 30 m, except for the thermal infra-red band. This is a significant improvement over the 79 m by 56 m resolution of the MSS. A major advantage of this is that ice margins and ice-surface features can be more precisely identified. More accurate glacier maps can be made, and smaller variations in termini positions of outlet glaciers can be monitored. Ice-surface features, such as crevasses, are more likely to be recorded on TM imagery, and examples are shown from Spitsbergen glaciers. The identification of such features is of major importance in studies of ice-surface velocities from Landsat imagery. For sea-ice applications, the ability to identify smaller floes is also important; for example, in the analysis of floe-size distributions.The only significant drawbacks to the use of Landsat TM data in glaciological studies are the expense, particularly in the more useful digital format, and the small amount of coverage yet available for the polar regions.

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Dowdeswell, J. A. „Comparison of Landsat Multispectral Scanner and Thematic Mapper Radiometric and Spatial Characteristics Over Glaciers (Abstract)“. Annals of Glaciology 9 (1987): 245. http://dx.doi.org/10.1017/s0260305500000835.

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For more than 10 years, images obtained from the four Landsat Multispectral Scanner (MSS) bands have provided important data for mapping and glaciological studies in the inaccessible polar regions. During this period, the specifications of the MSS have remained little altered, to allow data comparability. More recently, satellites 4 and 5 of the Landsat series have been equipped additionally with Thematic Mapper (TM) sensors. The TM has 7 bands in the visible, near infra-red, mid infra-red, and thermal infra-red, together with a larger dynamic range and improved spatial resolution relative to the MSS. The aim of this paper is to compare MSS and TM computer-compatible tapes (CCTs) from a glacierized area in order to demonstrate the advantages of using TM data in glaciological applications. The digital MSS and TM scenes compared were imaged simultaneously from Landsat 5 on 5 May 1984 over the north-west part of Spitsbergen, Svalbard (path 218, row 3). This location was selected because of the range of glaciological features present: numerous valley glaciers, the ice field of Holtedahlfonna, fast ice, and ice floes. Partially cloud-covered imagery was preferred, to allow comparison of the two sensors in terms of their ability to distinguish between clouds and snow. The time of year is also advantageous, in that Sun elevation (27°) is high enough for detector saturation to occur in MSS band 2 (Dowdeswell and McIntyre 1986). Surface-elevation data from airborne radio echo-sounding, and other ancilliary glaciological information, are also available for this part of Svalbard. Differences in the dynamic range and the wavelengths over which TM and MSS data are collected have two main implications for glaciological studies. First, snow and snow-covered ice masses can be distinguished easily from cloud cover in TM band 5 (1.57 to 1.78 μm). Snow appears dark whereas clouds are light at this wavelength. For example, thin clouds over part of Oscar II Land in Spitsbergen became apparent. In many MSS scenes of the Antarctic, the cloud-free ice-sheet surface has been misidentified as cloud-covered during quality-control analysis. Secondly, the wider dynamic range of the TM sensors means that saturation occurs less frequently over snow than was the case with MSS imagery. Digital analysis of MSS and TM scene radiance over Spitsbergen demonstrates this fact and implies that ice-surface topographic information will only rarely be degraded in TM imagery, although TM band 1 (0.45 to 0.52 μm) is most often saturated. The nominal spatial resolution of TM sensors is 30 m, except for the thermal infra-red band. This is a significant improvement over the 79 m by 56 m resolution of the MSS. A major advantage of this is that ice margins and ice-surface features can be more precisely identified. More accurate glacier maps can be made, and smaller variations in termini positions of outlet glaciers can be monitored. Ice-surface features, such as crevasses, are more likely to be recorded on TM imagery, and examples are shown from Spitsbergen glaciers. The identification of such features is of major importance in studies of ice-surface velocities from Landsat imagery. For sea-ice applications, the ability to identify smaller floes is also important; for example, in the analysis of floe-size distributions. The only significant drawbacks to the use of Landsat TM data in glaciological studies are the expense, particularly in the more useful digital format, and the small amount of coverage yet available for the polar regions.

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Zhang, Jin, Zengzhe Xi, Xinzhe Wang, Shenghan Gao, Xinyi Long und Feifei Guo. „Ferroelectric and Spectroscopic Properties of Ho3+/Yb3+ Co-Doped Pb(Mg1/3Nb2/3)O3-32PbTiO3 Crystal“. Crystals 12, Nr. 2 (04.02.2022): 225. http://dx.doi.org/10.3390/cryst12020225.

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In order to design a new multifunctional crystal with excellent ferroelectric and spectroscopic properties, experiments were carried out for Ho3+/Yb3+ co-doped Pb(Mg1/3Nb2/3)O3 -32PbTiO3 ferroelectric crystal using the flux method, the coercive field Ec of which is 11.86 kV/cm. Up-conversion luminescence emission bands, including an intense green emission band at 553 nm, a red band at 663 nm, and a weak infra-red band at 755 nm, are generated at 980 nm excitation. The main spectroscopic parameters, including radiative transition probability A(J′ − J), radiative lifetimes τrad, and branching ratios β, were predicted by applying Judd–Ofelt treatment. The obtained J-O intensity parameters are Ω2 = 0.531 × 10−20 cm2, Ω4 = 1.738 × 10−20 cm2, Ω6 = 0.530 × 10−20 cm2. The radiative lifetime of 5I7 level is 5.45 ms. The fluorescence lifetime of is 5F5 is 92.568 μs. The investigations show that Ho3+/Yb3+ co-doped Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 crystal is a new type of multifunctional crystal integrating ferroelectric and spectroscopic properties, which has a potential application in the developing innovative multifunctional devices and lasers.

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Chen, M. X., E. Perzon, N. Robisson, S. K. M. Jönsson, M. R. Andersson, M. Fahlman und M. Berggren. „Low band gap donor–acceptor–donor polymers for infra-red electroluminescence and transistors“. Synthetic Metals 146, Nr. 3 (November 2004): 233–36. http://dx.doi.org/10.1016/j.synthmet.2004.08.002.

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15

Banerji, Sourangsu, Monjurul Meem, Apratim Majumder, Curt Dvonch, Berardi Sensale-Rodriguez und Rajesh Menon. „Single flat lens enabling imaging in the short-wave infra-red (SWIR) band“. OSA Continuum 2, Nr. 10 (08.10.2019): 2968. http://dx.doi.org/10.1364/osac.2.002968.

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16

Beevi, M. Hussain, S. Vignesh, T. Pandiyarajan, P. Jegatheesan, R. Arthur James, N. V. Giridharan und B. Karthikeyan. „Synthesis and Antifungal Studies on CuO Nanostructures“. Advanced Materials Research 488-489 (März 2012): 666–70. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.666.

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We report, synthesis and antifungal activities of CuO nanoparticles. Particles are prepared through sol-gel method. X-ray diffraction studies show the particles are monoclinic (crystalline) in nature. Scanning electron microscopic measurements are carried out to understand the morphology of the prepared particles. Energy-dispersive X-ray spectroscopic measurements show that the prepared particles containing Cu and O. To identify the local structure of the particles Fourier transform infra red (FTIR) spectroscopic measurements were carried out showing vibrational bands of Cu-O and O-H band. Anti fungal studies were performed on the set of fungal using disk diffusion method and found that the prepared particles are suitable for antifungal activities.

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Khirunenko, Lyudmila I., Yu V. Pomozov, Mikhail G. Sosnin, A. V. Duvanskii, Vitor J. B. Torres, J. Coutinho, R. Jones, Patrick R. Briddon, Nikolay V. Abrosimov und H. Riemann. „Interstitial Carbon-Related Defects in Si_1-xGe_x Alloys“. Solid State Phenomena 131-133 (Oktober 2007): 59–64. http://dx.doi.org/10.4028/www.scientific.net/ssp.131-133.59.

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The interstitial carbon impurity (CI) vibrational modes in monocrystalline Si-rich SiGe were investigated by Fourier Transform Infra Red spectroscopy and density functional modelling. The two absorption bands of CI are found to be close to those in silicon, but show shifts in opposite directions with increasing Ge content. The transversal mode band at 932 cm-1 shifts slightly to the high frequency side, while the longitudinal mode at 922 cm-1 suffers a pronounced red-shift. Each Ci-related band is found to consist of two components. An annealing of CI in Si1-xGex occures in two stage. During the first stage (210-250 K) the main components of bands anneals and revealed components grow in intensity. At T>250 K all components disappear. Two component structure of bands is suppose most likely correspond to different combinations of Si and Ge atoms in the neighbourhood of the carbon atom. The interstitial carbon defect was modelled by a supercell density-functional pseudopotential method (AIMPRO) for alloys with 4.69% Ge concentration. From energetics, it has been found that each Ge-C bond costs at least 0.4 eV in excess of a Si-C bond. However, structures where Ge atoms are second neighbors to the C atom are marginally bound, and may explain the two-component band structure in the absorption measurements. The vibrational mode frequencies taken from several randomly generated SiGe cells produce the observed opposite shifts for the transverse and longitudinal modes.

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WAKAI, Kazunori, Shoshi SHIMIZU, Masanori SONOBE und Shinji SAKAI. „Two-dimensional temperature distribution measurement by an infra-red 2-band emission CT pyrometer.“ Transactions of the Japan Society of Mechanical Engineers Series B 54, Nr. 508 (1988): 3553–58. http://dx.doi.org/10.1299/kikaib.54.3553.

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Newton-Howes, J. C., und R. J. Fleming. „Thermoluminescence and hydroxyl defects associated with broad-band infra red absorption in synthetic quartz“. Physics and Chemistry of Minerals 17, Nr. 1 (Januar 1990): 27–33. http://dx.doi.org/10.1007/bf00209222.

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20

Pitigala, P. K. D. D. P., Y. F. Lao, A. G. U. Perera, L. H. Li, E. H. Linfield und H. C. Liu. „Performance improvements of a split-off band infra-red detector using a graded barrier“. Journal of Applied Physics 115, Nr. 6 (14.02.2014): 063105. http://dx.doi.org/10.1063/1.4865501.

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Omont, A., S. H. Moseley, T. Forveille, P. M. Harvey und L. Likkel. „IRAS09371+1212: A Unique Red Giant With Strong Emission in the 40-70 Micron Bands of Ice“. International Astronomical Union Colloquium 106 (1989): 370. http://dx.doi.org/10.1017/s0252921100063284.

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IRAS 09371+1212 (sometimes called the Frosty Leo nebula) is up to now an absolutely unique object. Its stellar nature has been proved by the detection of circumstellar CO (J = 1-0) by Forveille et al. (1987), and by its stellar M giant spectral type, although its infrared colors and its visible appearance could have suggested a galaxy (Condon and Broderick 1986). It displays unique IRAS far infra-red colors which have been attributed by Forveille et al. (1987) to a strong emission in the 40-70 micron bands of ice. The presence of an extremely large quantity of ice is confirmed by extraordinary strength of its 3.1 micron absorption band (Rouan et al. 1988; Hodapp et al. 1988; Geballe et al. 1988).

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Remedios, J. J., G. Allen, A. M. Waterfall, H. Oelhaf und A. Kleinert. „Detection of organic compound signatures in infra-red, limb emission spectra observed by the MIPAS-B2 instrument“. Atmospheric Chemistry and Physics Discussions 6, Nr. 5 (11.10.2006): 10021–61. http://dx.doi.org/10.5194/acpd-6-10021-2006.

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Abstract. Organic compounds play a central role in troposphere chemistry and increasingly are a viable target for remote sensing observations. In this paper, infra-red spectral features of three organic compounds are investigated in thermal emission spectra recorded by a balloon-borne instrument, MIPAS-B2, operating at high spectral resolution. It is demonstrated, for the first time, that PAN and acetone can be detected in infra-red remote sensing spectra of the upper troposphere; detection results are presented at tangent altitudes of 10.4 km and 7.5 km (not acetone). In addition, the results provide the first observation of spectral features of formic acid in thermal emission, as opposed to solar occultation, and confirm that concentrations of this gas are likely to be measurable in the free troposphere, given accurate spectroscopic data. For PAN, two bands are observed centred at 794 cm−1 and 1163 cm−1. For acetone and formic acid, one band has been detected for each so far with band centres at 1218 cm−1 and 1105 cm−1 respectively. Mixing ratios inferred at 10.4 km tangent altitude are 180 pptv and 530 pptv for PAN and acetone respectively, and 200 pptv for formic acid with HITRAN 2000 spectroscopy. Accuracies are on the order of 30 to 50%. The detection technique applied here is verified by examining weak but known signatures of CFC-12 and HCFC-22 in the same spectral regions as those of the organic compounds, with results confirming the quality of both the instrument and the radiative transfer model. The results suggest the possibility of global sensing of the organic compounds studied here which would be a major step forward in verifying and interpreting global tropospheric model calculations.

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Remedios, J. J., G. Allen, A. M. Waterfall, H. Oelhaf, A. Kleinert und D. P. Moore. „Detection of organic compound signatures in infra-red, limb emission spectra observed by the MIPAS-B2 balloon instrument“. Atmospheric Chemistry and Physics 7, Nr. 6 (26.03.2007): 1599–613. http://dx.doi.org/10.5194/acp-7-1599-2007.

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Abstract. Organic compounds play a central role in troposphere chemistry and increasingly are a viable target for remote sensing observations. In this paper, infra-red spectral features of three organic compounds are investigated in thermal emission spectra recorded on a flight on 8 May 1998 near Aire sur l'Adour by a balloon-borne instrument, MIPAS-B2, operating at high spectral resolution. It is demonstrated, for the first time, that PAN and acetone can be detected in infra-red remote sensing spectra of the upper troposphere; detection results are presented at tangent altitudes of 10.4 km and 7.5 km (not acetone). In addition, the results provide the first observation of spectral features of formic acid in thermal emission, as opposed to solar occultation, and confirm that concentrations of this gas are measurable in the mid-latitude upper troposphere, given accurate spectroscopic data. For PAN, two bands are observed centred at 794 cm−1 and 1163 cm−1. For acetone and formic acid, one band has been detected for each so far with band centres at 1218 cm−1 and 1105 cm−1 respectively. Mixing ratios inferred at 10.4 km tangent altitude are 180 pptv and 530 pptv for PAN and acetone respectively, and 200 pptv for formic acid with HITRAN 2000 spectroscopy. Accuracies are on the order of 15 to 40%. The detection technique applied here is verified by examining weak but known signatures of CFC-12 and HCFC-22 in the same spectral regions as those of the organic compounds, with results confirming the quality of both the instrument and the radiative transfer model. The results suggest the possibility of global sensing of the organic compounds studied here which would be a major step forward in verifying and interpreting global tropospheric model calculations.

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Le Bris, A., N. Chehata, X. Briottet und N. Paparoditis. „SPECTRAL BAND SELECTION FOR URBAN MATERIAL CLASSIFICATION USING HYPERSPECTRAL LIBRARIES“. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-7 (07.06.2016): 33–40. http://dx.doi.org/10.5194/isprsannals-iii-7-33-2016.

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In urban areas, information concerning very high resolution land cover and especially material maps are necessary for several city modelling or monitoring applications. That is to say, knowledge concerning the roofing materials or the different kinds of ground areas is required. Airborne remote sensing techniques appear to be convenient for providing such information at a large scale. However, results obtained using most traditional processing methods based on usual red-green-blue-near infrared multispectral images remain limited for such applications. A possible way to improve classification results is to enhance the imagery spectral resolution using superspectral or hyperspectral sensors. In this study, it is intended to design a superspectral sensor dedicated to urban materials classification and this work particularly focused on the selection of the optimal spectral band subsets for such sensor. First, reflectance spectral signatures of urban materials were collected from 7 spectral libraires. Then, spectral optimization was performed using this data set. The band selection workflow included two steps, optimising first the number of spectral bands using an incremental method and then examining several possible optimised band subsets using a stochastic algorithm. The same wrapper relevance criterion relying on a confidence measure of Random Forests classifier was used at both steps. To cope with the limited number of available spectra for several classes, additional synthetic spectra were generated from the collection of reference spectra: intra-class variability was simulated by multiplying reference spectra by a random coefficient. At the end, selected band subsets were evaluated considering the classification quality reached using a rbf svm classifier. It was confirmed that a limited band subset was sufficient to classify common urban materials. The important contribution of bands from the Short Wave Infra-Red (SWIR) spectral domain (1000–2400 nm) to material classification was also shown.

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Le Bris, A., N. Chehata, X. Briottet und N. Paparoditis. „SPECTRAL BAND SELECTION FOR URBAN MATERIAL CLASSIFICATION USING HYPERSPECTRAL LIBRARIES“. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences III-7 (07.06.2016): 33–40. http://dx.doi.org/10.5194/isprs-annals-iii-7-33-2016.

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In urban areas, information concerning very high resolution land cover and especially material maps are necessary for several city modelling or monitoring applications. That is to say, knowledge concerning the roofing materials or the different kinds of ground areas is required. Airborne remote sensing techniques appear to be convenient for providing such information at a large scale. However, results obtained using most traditional processing methods based on usual red-green-blue-near infrared multispectral images remain limited for such applications. A possible way to improve classification results is to enhance the imagery spectral resolution using superspectral or hyperspectral sensors. In this study, it is intended to design a superspectral sensor dedicated to urban materials classification and this work particularly focused on the selection of the optimal spectral band subsets for such sensor. First, reflectance spectral signatures of urban materials were collected from 7 spectral libraires. Then, spectral optimization was performed using this data set. The band selection workflow included two steps, optimising first the number of spectral bands using an incremental method and then examining several possible optimised band subsets using a stochastic algorithm. The same wrapper relevance criterion relying on a confidence measure of Random Forests classifier was used at both steps. To cope with the limited number of available spectra for several classes, additional synthetic spectra were generated from the collection of reference spectra: intra-class variability was simulated by multiplying reference spectra by a random coefficient. At the end, selected band subsets were evaluated considering the classification quality reached using a rbf svm classifier. It was confirmed that a limited band subset was sufficient to classify common urban materials. The important contribution of bands from the Short Wave Infra-Red (SWIR) spectral domain (1000–2400 nm) to material classification was also shown.

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Yao, Kai-Lun, und Xiao-Lin Chu. „Intensity of the Far Infra-Red Absorption Band for a Disordered Polymer at Low Temperature“. Japanese Journal of Applied Physics 26, S3-1 (01.01.1987): 769. http://dx.doi.org/10.7567/jjaps.26s3.769.

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Rich, Peter R., A. John Moody und W. John Ingledew. „Detection of a near infra-red absorption band of ferrohaem a3 in cytochrome c oxidase“. FEBS Letters 305, Nr. 3 (06.07.1992): 171–73. http://dx.doi.org/10.1016/0014-5793(92)80659-5.

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Katz, J., Y. Zhang und W. I. Wang. „Normal incidence infra-red absorption from intersub-band transitions inp-type GaInAs/AIInAs quantum wells“. Electronics Letters 28, Nr. 10 (07.05.1992): 932–34. http://dx.doi.org/10.1049/el:19920590.

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29

Noranizah, A., K. Azman, H. Azhan, E. S. Nurbaisyatul und Mardhiah Abdullah. „FTIR and UV-Vis-NIR Spectral Studies of Borotellurite Glass“. Advanced Materials Research 1107 (Juni 2015): 391–96. http://dx.doi.org/10.4028/www.scientific.net/amr.1107.391.

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A glass system based on composition of 80TeO2-(10-x) B2O3 -10PbO-xNd2O3, where 0.0mol% ≤ x ≥ 2.5mol% was successfully prepared by melt-quenching method. The structural and optical behavior of the Nd3+ doped borotellurite glasses are well studied by mean of their FTIR, XRD as well as UV-Vis -NIR spectroscopy. The XRD pattern obtained confirms the amorphous nature of the glass. Meanwhile, the infra-red absorption spectra of glass samples obtained are recorded using an FTIR spectrometer in the wave number ranging from 400 to 4000 cm-1. The bands observed were attributed to the different modes of vibrations of Te-O band. From the absorption spectral measurements, the value of optical band gap (Eopt) and the Urbach energy (ΔE) values were calculated with the results were then been discussed nor reported. Quantitative justification of these absorption bands shows that the values of the experimental wave number for most absorption bands are in agreement with the theoretical ones. Optical absorption spectra show that the absorption edge has a tail extending towards lower energies. In general, an increment or a decrement in Urbach’s energy can be considered to be due to a deformation of glass network.

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Albano, Maurizio, A. Manu Haddad und Nathan Bungay. „Is the Dry-Band Characteristic a Function of Pollution and Insulator Design?“ Energies 12, Nr. 19 (21.09.2019): 3607. http://dx.doi.org/10.3390/en12193607.

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This paper assesses the dry-band formation and location during artificial pollution tests performed on a 4-shed 11kV insulator with conventional and textured surface designs in a clean-fog chamber and with the application of a voltage ramp-shape source. The different designs present the same overall geometrical dimensions, but the textured ones are characterized by the application of a patented insulator surface design. Three pollution levels, extremely high, high and moderate, were considered. A newly developed MATLAB procedure is able to automatically recognize the perimeter of the insulator, the trunk and shed areas on infra-red recordings. In addition, using the vertical axis identification, all trunks are subdivided into zones and into left and right areas, significantly increasing the capability of abnormalities detection. Any temperature increase within these areas enables to detect the appearance and the extension of dry bands. The results of the analysis of the statistical location and extension development over time of the dry bands during these set of comparative tests show a clear distinction between designs and pollution levels. These results may offer interesting design guidelines for dry-band control.

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Singh, D., G. S. Mudahar, K. S. Thind und Hardev Singh Virk. „Structural Investigations of Gamma-Irradiated PbO Glasses“. Solid State Phenomena 239 (August 2015): 98–109. http://dx.doi.org/10.4028/www.scientific.net/ssp.239.98.

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The effects of gamma radiations on the optical, physical and structural properties of zinc lead borate xZnO-2xPbO-(1-3x)B2O3 and zinc lead borosilicate xZnO-2xPbO-1/2(1-3x)B2O3-1/2(1-3x)SiO2 glasses have been investigated. Differential Scanning Calorimetry (DSC), Ultraviolet-Visible (UV-Vis) and Fourier Transmission Infra-red (FTIR) spectroscopic techniques have been used to compare the properties of samples before and after gamma irradiation by a dose of 2.5 kGy. The variation of density, optical band gap (Eg), IR absorption bands and glass transition temperature (Tg) indicates that the structure of glasses changes due to irradiation. The radiation induced changes created by-ray in the optical, physical and thermal parameters in both the prepared series of glasses have been discussed for their possible application as radiation shielding material.

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Heintze, J. R. W. „The Utrecht Photometric System (≡ UPS) and Some Results With it“. International Astronomical Union Colloquium 107 (1989): 257–60. http://dx.doi.org/10.1017/s0252921100087832.

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The Utrecht Photometric System (≡ UPS) is a narrow-band photometric system (Δλ ⩽ 10 nm) characterized by wavelength regions in which no telluric lines and nearly no stellar/interstellar spectral lines are present. Because in the near-infra red the density of spectral lines is much less than in the visible and blue, filters with transmission as far as possible into the near-infra red are necessary. Photomultipliers with GaAs cathodes, which have a high sensitivity up to 900 nm have enabled the design of the UPS. In Figure 1 the absoluteFigure 1. Comparison of responsivities of several cathodes.Figure 2. The positions of the UPS filters with respect to solar and telluric lines.responsivity of the GaAs cathode is compared with S1, S4, S13, S20 and S20 extended cathodes. In Figure 2a the transmission curves of the UPS (474, 579, 672, 781 and 871 nm) are given as a function of wavelength (Provoost (1980) gives larger graphs for the transmissions). Figure 2b shows in the lower part over 20 Å summed up equivalent widths of solar lines as a function of wavelength. In the upper part of Figure 2b the same is done for the telluric lines.

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Clark, B. J. M., D. R. Anderson, N. Madhusudhan, C. Hellier, A. M. S. Smith und A. Collier Cameron. „Thermal emission of WASP-48b in the Ks-band“. Astronomy & Astrophysics 615 (Juli 2018): A86. http://dx.doi.org/10.1051/0004-6361/201527071.

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We report a detection of thermal emission from the hot Jupiter WASP-48b in the Ks-band. We used the Wide-field Infra-red Camera on the 3.6-m Canada-France Hawaii Telescope to observe an occultation of the planet by its host star. From the resulting occultation lightcurve we find a planet-to-star contrast ratio in the Ks-band of 0.136 ± 0.014%, in agreement with the value of 0.109 ± 0.027% previously determined. We fit the two Ks-band occultation lightcurves simultaneously with occultation lightcurves in the H-band and the Spitzer 3.6- and 4.5-μm bandpasses, radial velocity data, and transit lightcurves. From this, we revise the system parameters and construct the spectral energy distribution (SED) of the dayside atmosphere. By comparing the SED with atmospheric models, we find that both models with and without a thermal inversion are consistent with the data. We find the planet’s orbit to be consistent with circular (e < 0.072 at 3σ).

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Pomeroy, J. W., und D. H. Male. „Optical Properties of Blowing Snow“. Journal of Glaciology 34, Nr. 116 (1988): 3–10. http://dx.doi.org/10.1017/s0022143000008996.

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Abstract Calculation procedures are developed and results shown for the exact calculation of extinction and meteorological visual range using the blowing-snow mass in the atmosphere and particle radius. Results of the calculations show: (1) For monochromatic radiation, geometrical optics approximations of the extinction efficiency are found to provide results of only moderate accuracy in calculating the extinction of radiation by a single particle. (2) For broad-band radiation, the geometrical optics approximation is sufficiently accurate for many single-particle measurement instruments and applications, except in the infra-red band where Mie theory should be used. (3) For typical blowing-snow particle-size distributions, the shape parameter of the distribution of particle radii and the mean particle radius are very important in broad-band extinction and visual-range modelling. Estimates of blowing-snow quantities from broad-band extinction measurements or visual range from blowing-snow quantities should address the shape and mean value of the snow-particle radius distribution.

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Pomeroy, J. W., und D. H. Male. „Optical Properties of Blowing Snow“. Journal of Glaciology 34, Nr. 116 (1988): 3–10. http://dx.doi.org/10.3189/s0022143000008996.

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AbstractCalculation procedures are developed and results shown for the exact calculation of extinction and meteorological visual range using the blowing-snow mass in the atmosphere and particle radius. Results of the calculations show: (1) For monochromatic radiation, geometrical optics approximations of the extinction efficiency are found to provide results of only moderate accuracy in calculating the extinction of radiation by a single particle. (2) For broad-band radiation, the geometrical optics approximation is sufficiently accurate for many single-particle measurement instruments and applications, except in the infra-red band where Mie theory should be used. (3) For typical blowing-snow particle-size distributions, the shape parameter of the distribution of particle radii and the mean particle radius are very important in broad-band extinction and visual-range modelling. Estimates of blowing-snow quantities from broad-band extinction measurements or visual range from blowing-snow quantities should address the shape and mean value of the snow-particle radius distribution.

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Fajrah, M. C., und F. Mirnawati. „Forming of absorption band from yellow cane (Sacharum Officindrum) carbonized using Fourier Transformation Infra-Red (FTIR)“. Journal of Physics: Conference Series 1242 (Juni 2019): 012034. http://dx.doi.org/10.1088/1742-6596/1242/1/012034.

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37

Afaq, A., Abu Bakar, Nimra Khan und Anila Asif. „Reststrahlen band studies in cubic perovskite materials SmXO3 (X = Al,Co) by computational investigations“. International Journal of Modern Physics B 34, Nr. 21 (20.08.2020): 2050206. http://dx.doi.org/10.1142/s0217979220502069.

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A theoretical study of SmXO3 ([Formula: see text], Co) cubic perovskites for vibrational properties and Reststrahlen band is done within the framework of Density Functional Perturbation Theory (DFPT) implemented in Quantum ESPRESSO. The vibrational properties of the Samarium-based perovskites are figured using Martins–Troullier pseudo potentials. The phonon density of states and phonon dispersion curves in first Brillouin zone are computed and discussed in which two optical phonon frequencies, [Formula: see text] and [Formula: see text], are targeted to find Reststrahlen band for these materials. No imaginary frequency was noted, which shows the structural stability of both perovskites in cubic state. Reststrahlen bandgap and Lyddane–Sachs–Teller (LST) relation for these materials are calculated using optical phonon frequencies and applications are specified. Reststrahlen band of both materials is found to exist in the Far Infra-red region (ranging from 0.3 to 6.0 THz) showing that they can be identified by throwing light of Infrared region upon them in geological applications.

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Sun, Xiaohui, und Lei Guan. „Arctic Sea Ice Albedo Estimation from Fengyun-3C/Visible and Infra-Red Radiometer“. Remote Sensing 16, Nr. 10 (12.05.2024): 1719. http://dx.doi.org/10.3390/rs16101719.

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The sea ice albedo can amplify global climate change and affect the surface energy in the Arctic. In this paper, the data from Visible and Infra-Red Radiometer (VIRR) onboard Fengyun-3C satellite are applied to derive the Arctic sea ice albedo. Two radiative transfer models, namely, 6S and FluxNet, are used to simulate the reflectance and albedo in the shortwave band. Clear sky sea ice albedo in the Arctic region (60°~90°N) from 2016 to 2019 is derived through the physical process, including data preprocessing, narrowband to broadband conversion, anisotropy correction, and atmospheric correction. The results are compared with aircraft measurements and AVHRR Polar Pathfinder-Extended (APP-x) albedo product and OLCI MPF product. The bias and standard deviation of the difference between VIRR albedo and aircraft measurements are −0.040 and 0.071, respectively. Compared with APP-x product and OLCI MPF product, a good consistency of albedo is shown. And analyzed together with melt pond fraction, an obvious negative relationship can be seen. After processing the 4-year data, an obvious annual trend can be observed. Due to the influence of snow on the ice surface, the average surface albedo of the Arctic in March and April can reach more than 0.8. Starting in May, with the ice and snow melting and melt ponds forming, the albedo drops rapidly to 0.5–0.6. Into August, the melt ponds begin to freeze and the surface albedo increases.

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Dahham, Najat A. „Influence of cobalt substitution on the properties of Ni0.95-xCoxCu0.05Fe2O4 ferrite nanoparticles“. Iraqi Journal of Physics (IJP) 16, Nr. 38 (10.09.2018): 42–55. http://dx.doi.org/10.30723/ijp.v16i38.94.

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Cobalt substituted nickel copper ferrite samples with general formula Ni0.95-xCoxCu0.05Fe2O4, where (x= 0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) were prepared by solid-state reactions method at 1373 K for 4h. The samples prepared were examined by X-ray diffraction (XRD(, atomic force microscope (AFM), Fourier transform infra-red spectroscopy (FTIR) and Vickers hardness. X-ray diffraction patterns confirm the formation of a single phase of cubic spinel structure in all the prepared samples . XRD analysis showed that the increase in the cobalt concentration causes an increase in the lattice constant, bulk density (ρm) and the x-ray density (ρx), whereas porosity (p) and crystallite size (D) decrease. The Topography of the surface observed was found to be more uniform and homogeneous when the cobalt concentration increases, leading to a decrease in the roughness of the surface while average grains size increases. The FTIR spectra show two absorption bands, namely the high frequency band (υ1) in the range (1078-1081) cm-1 and the low frequency band (υ2) in the range (418–459) cm-1, which due to the vibrations of the tetrahedral and octahedral sites of Fe+3–O−2, respectively, these bands confirm the spinel structure of the prepared ferrite nanoparticles. Vickers hardness was found to increase with cobalt concentration increases.

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W�thrich, M. „Thermal infra-red underflights compared to ERS-1 C-band synthetic aperture radar focusing soil moisture distribution“. Theoretical and Applied Climatology 53, Nr. 1-3 (1996): 69–78. http://dx.doi.org/10.1007/bf00866412.

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Kalenik, Jerzy, Irena Majerz, Lucjan Sobczyk, Eugeniusz Grech und Mustafa M. M. Habeeb. „Infra-red and 35Cl nuclear quadrupole resonance studies of hydrogen bonded adducts of 2-chlorobenzoic acid derivatives“. Collection of Czechoslovak Chemical Communications 55, Nr. 1 (1990): 80–90. http://dx.doi.org/10.1135/cccc19900080.

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The IR and 35Cl NQR spectra of several solid hydrogen bonded adducts of o-chlorobenzoic acids and amines were studied over the broad ΔpKa range. Both IR and NQR spectra yield the indication of the existence of an inversion (critical) ΔpKa range where the proton transfer takes place. The critical point is distinguished by a deep minimum of the position of the gravity centre of the broad protonic band. The mechanism of the transmittance of the charge distribution within the hydrogen bridge on the electric field gradient in the position of quadrupole Cl nuclei attached to the phenyl ring is analysed.

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Adeniyi, Adedeji Olumide, D. E. A. Boyro, Istifanus Yarkasuwa Chindo und A. A. Mahmoud. „Spectrophotometric and infra-red analyses of azo reactive dyes derived from 2-methyl-3-(2’- methylphenyl)-6-arylazo-4- oxoquinazoline“. Science World Journal 18, Nr. 2 (20.10.2023): 231–39. http://dx.doi.org/10.4314/swj.v18i2.10.

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Ultraviolet-visible and infrared spectroscopic techniques were used to determine the possible composition and functional groups present in a series of quinazoline based mono azo reactive dyes (DM1-5) which was prepared by coupling 2-methyl-3-(2’- methylphenyl)-6-arylazo-4-oxoquinazoline diazonium solution with five (5) cyanurated coupling components . The result of visible absorption spectra showed that the λmax obtained for each dye depends on the coupling component used and that the λmax tend to shift to the shorter wavelength (hypsochromic shift) as the auxochromes appear to have influence on the absorption peak of the dyes... The IR spectral showed all the characteristics and representative of azo reactive dyes, with characteristic band in the range of 3400 - 3309 cm-1 indicating the presence of -OH and –NH stretching vibration, 1382 - 1049 cm-1 for the presence of –C-N, 1141-1010 cm-3 for –S=0 and 925 - 56 cm-1 for the presence of - C-Cl . The azo band occurred in the region of 1458 - 1411 cm-1 which is due to stretching vibration of the -N=N- group. A strong band at 1643 - 1604 cm-1 is due to the stretching vibration of -C=O group of the quinazoline compound. However, the IR spectrum did not actually reveal the chemical structure of the reactive dyes being studied. Further studies could be conducted using GCMS and NMR spectroscopy to confirm the structure of the dyes.

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Zurlo, A., A. Vigan, C. Moutou, D. Mesa, R. Gratton, M. Langlois, J. L. Beuzit et al. „IRDIS, the dual-band imager camera of SPHERE: testing the performances in laboratory“. Proceedings of the International Astronomical Union 8, S299 (Juni 2013): 78–79. http://dx.doi.org/10.1017/s1743921313007965.

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AbstractNext year the second generation instrument SPHERE will begin science operations at the Very Large Telecope (ESO). This instrument will be dedicated to the search for exoplanets through the direct imaging techniques, with the new generation extreme adaptive optics. In this poster, we present the performances of one of the focal instruments, the Infra-Red Dual-beam Imaging and Spectroscopy (IRDIS). All the results have been obtained with tests in laboratory, simulating the observing conditions in Paranal. We tested several configurations using the sub-system Integral Field Spectrograph (IFS) in parallel and simulating long coronographic exposures on a star, calibrating instrumental ghosts, checking the performance of the adaptive optics system and reducing data with the consortium pipeline. The contrast one can reach with IRDIS is of the order of 10−6 at 0.5 arcsec separation from the central star.

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Piskunov, S., O. Lisovski, A. Gopejenko, L. Trinkler, M. M. C. Chou und L. W. Chang. „DFT Simulations of Zn_xMg_1–XO Solid Solutions for Solar-Blind UV Sensors: Evaluation of Electronic Structure and Phase Stability“. Latvian Journal of Physics and Technical Sciences 59, Nr. 6 (01.12.2022): 3–11. http://dx.doi.org/10.2478/lpts-2022-0042.

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Abstract In this research, density functional theory accompanied with linear combination of atomic orbitals (LCAO) method is applied to study the atomic and electronic structure of wurtzite and rocksalt ZnxMg1−xO pseudobinary compounds in their bulk phases. Calculated band gaps of ZnxMg1−xO solid solutions under study are further validated by means of spectroscopic ellipsometry and optical absorption. In agreement with an experiment, it is predicted that increase of Zn content in ZnxMg1−xO leads to narrowing of its band gap for both wurtzite and rocksalt phases. The calculated infra-red (IR) spectra show that the IR peaks are shifted towards larger frequencies along with decrease of Zn content. Presence of imaginary phonon frequencies in rocksalt ZnxMg1−xO of x > 0.625 allows us to suggest that it is necessary to use properly oriented substrates for epitaxial growth to overcome polycrystallinity inZnxMg1−xO thin films at concentration x = 0.4 – 0.6.

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Widyaningrum, Bernadeta Ayu, Dita Apriani, Putri Amanda, Ismadi Ismadi und Sutanto Sutanto. „SYNTHESIS AND CHARACTERIZATION: COMPOSITE OF GRAPHENE OXIDE BASED PALM KERNEL SHELL WASTE WITH FE3O4“. Jurnal Sains Materi Indonesia 22, Nr. 2 (16.08.2021): 101. http://dx.doi.org/10.17146/jsmi.2021.22.3.6310.

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SYNTHESIS AND CHARACTERIZATION: COMPOSITE OF GRAPHENE OXIDE BASED PALM KERNEL SHELL WASTE WITH Fe3O4. In this study, GO-Fe3O4 were fabricated by co-precipitation technique and the graphene oxide (GO) were synthesized from an agricultural biomass, palm kernel shell, via Hummer’s method. Field Emission Scanning Electron Microscopy and Energy Dispersive Spectrum (FESEM-EDS), Fourier Transform Infra-Red (FT-IR) spectroscopy, X-Ray Diffractometer (XRD), and Raman spectroscopy were used to analysis the successful attachment of Fe3O4 onto the surface of GO. Morphology observation showed that Fe3O4 were heterogeneously deposited on the surface of GO. FT-IR spectra shows peak that incorporated to oxygenated functional groups and sharp peak at 586 cm-1 confirmed to lattice absorption of Fe3O4. The percentage of composition of GO-Fe3O4 was characterized by energy dispersive spectroscopy and the results also confirmed in XRD exhibits similar properties with JCPDS 19-0629 for magnetite more dominant than GO. From Raman spectroscopy analysis shows that 1343.82 cm-1 (D-band) and 1584.62 cm-1 (G-band) and 2698 cm-1 (2D-band) indicates GO and GO-Fe3O4 were successfully synthesized.

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Esa, Mazlina, Mohd Khairul Hisham Ismail, Noor Asniza Murad, Nik Noordini Nik Abd. Malik, Mohd Fairus Mohd Yusoff und Shipun Anuar Hamzah. „Parametric Performances of a Petahertz Band Nano-Patch Dipole Antenna on Electrical Field Distribution for Energy Harvesting“. Applied Mechanics and Materials 781 (August 2015): 454–57. http://dx.doi.org/10.4028/www.scientific.net/amm.781.454.

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There is an important need to investigate the enhancement of electrical field in visible and near infra-red region for a nanopatch antenna. This paper presents the relationship between metal thicknesses and electrical field with dedicated amount of dielectric material by using a typical design concept of a patch antenna. Two metal thicknesses have been considered, the radiating patch and ground layer. It was found that the decrement of electrical field can be clearly observed through parametric investigation of the metal thickness. Additionally, the resonance peak response is similar to an electrical field which decreases with increasing metal thickness. It can be concluded that the change of an antenna parameter is capable to control two properties for a desired application.

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Jakovac, Josip, Leonardo Marušić, Denise Andrade-Guevara, Julio C. Chacón-Torres und Vito Despoja. „Infra-Red Active Dirac Plasmon Serie in Potassium Doped-Graphene (KC8) Nanoribbons Array on Al2O3 Substrate“. Materials 14, Nr. 15 (30.07.2021): 4256. http://dx.doi.org/10.3390/ma14154256.

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A theoretical formulation of the electromagnetic response in graphene ribbons on dielectric substrate is derived in the framework of the ab initio method. The formulation is applied to calculate the electromagnetic energy absorption in an array of potassium-doped graphene nanoribbons (KC8-NR) deposited on a dielectric Al2O3 substrate. It is demonstrated that the replacement of the flat KC8 by an array of KC8-NR transforms the Drude tail in the absorption spectra into a series of infrared-active Dirac plasmon resonances. It is also shown that the series of Dirac plasmon resonances, when unfolded across the extended Brillouin zones, resembles the Dirac plasmon. The Dirac plasmon resonances’ band structure, within the first Brillouin zone, is calculated. Finally, an excellent agreement between the theoretical absorption and recent experimental results for differential transmission through graphene on an SiO2/Si surface is presented. The theoretically predicted micrometer graphene nanoribbons intercalation compound (GNRIC) in a stage-I-like KC8 is confirmed to be synthesized for Dirac plasmon resonances.

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Santillan, Jojene Rendon, und Meriam Makinano-Santillan. „ANALYSIS OF IN-SITU SPECTRAL REFLECTANCE OF SAGO AND OTHER PALMS: IMPLICATIONS FOR THEIR DETECTION IN OPTICAL SATELLITE IMAGES“. ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-3 (23.04.2018): 185–91. http://dx.doi.org/10.5194/isprs-annals-iv-3-185-2018.

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We present a characterization, comparison and analysis of in-situ spectral reflectance of Sago and other palms (coconut, oil palm and nipa) to ascertain on which part of the electromagnetic spectrum these palms are distinguishable from each other. The analysis also aims to reveal information that will assist in selecting which band to use when mapping Sago palms using the images acquired by these sensors. The datasets used in the analysis consisted of averaged spectral reflectance curves of each palm species measured within the 345&ndash;1045&thinsp;nm wavelength range using an Ocean Optics USB4000-VIS-NIR Miniature Fiber Optic Spectrometer. This in-situ reflectance data was also resampled to match the spectral response of the 4 bands of ALOS AVNIR-2, 3 bands of ASTER VNIR, 4 bands of Landsat 7 ETM+, 5 bands of Landsat 8, and 8 bands of Worldview-2 (WV2). Examination of the spectral reflectance curves showed that the near infra-red region, specifically at 770, 800 and 875 nm, provides the best wavelengths where Sago palms can be distinguished from other palms. The resampling of the in-situ reflectance spectra to match the spectral response of optical sensors made possible the analysis of the differences in reflectance values of Sago and other palms in different bands of the sensors. Overall, the knowledge learned from the analysis can be useful in the actual analysis of optical satellite images, specifically in determining which band to include or to exclude, or whether to use all bands of a sensor in discriminating and mapping Sago palms.

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Lallement, R., N. L. J. Cox, J. Cami, J. Smoker, A. Fahrang, M. Elyajouri, M. A. Cordiner et al. „The EDIBLES survey II. The detectability of C60+ bands“. Astronomy & Astrophysics 614 (Juni 2018): A28. http://dx.doi.org/10.1051/0004-6361/201832647.

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Gas phase spectroscopic laboratory experiments for the buckminsterfullerene cation C60+ have resulted in accurate rest wavelengths for five C60+ transitions that have been compared with diffuse interstellar bands (DIBs) in the near infra-red. Detecting these in astronomical spectra is difficult because of the strong contamination of ground-based spectra by atmospheric water vapor, to the presence of weak and shallow stellar lines and/or blending with other weak DIBs. The detection of the two strong bands has been claimed by several teams, and the three additional and weaker bands have been detected in a few sources. Certain recent papers have argued against the identification of C60+ based on spectral analyses claiming (i) a large variation in the ratio of the equivalent widths of the 9632 and 9577 Å bands, (ii) a large redshift of the 9632 Å band for the Orion star HD 37022, and (iii) the non-detection of the weaker 9428 Å DIB. Here we address these three points: (i) We show that the model stellar line correction for the 9632 Å DIB overestimates the difference between the strengths of the lines in giant and dwarf star spectra, casting doubts on the conclusions about the ratio variability. (ii) Using high quality stellar spectra from the ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES), recorded with the ESO/Paranal Ultraviolet Echelle Spectrograph (UVES) in about the same atmospheric conditions, we find no wavelength shift in the 9632 Å band toward HD 37022. (iii) Using EDIBLES spectra and data from the Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) at CFHT we show that the presence of a weak 9428 Å band cannot be ruled out, even in the same observations that a previous study claimed it was not present.

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50

Cullis, Anthony G. „Crystalline nanostructures in porous silicon and their relation to optical and electronic properties“. Proceedings, annual meeting, Electron Microscopy Society of America 51 (01.08.1993): 814–15. http://dx.doi.org/10.1017/s0424820100149908.

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Although Si normally emits only extremely weak infrared photoluminescence (PL) due to its relatively small and indirect band gap, light-emitting devices based upon Si would find many applications in both VLSI and display technologies. Therefore, there has been much interest in the recent demonstration of very efficient visible light emission from highly porous, electrochemically etched Si. Although it was originally proposed that the efficient PL was due to recombination of quantum-confined carriers in pore walls, evidence for this was only indirect and transmission electron microscopy (TEM) studies have been required to provide a detailed understanding of the light emission mechanism.Porous Si samples are generally prepared by anodization in HF solution and porosities as high as ∼80% are required for efficient PL emission. Typical PL spectra from highly porous Si are shown in Fig. 1 where it is evident that emission is usually in the red and near infra-red regions of the spectrum.

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