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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Using Reflectance Spectroscopy to Characterize Surface Landforms and Volcanic Deposits on Deception Island (Antarctica)
摘要： Deception Island is an active volcano in the Antarctic Peninsula region, affected by different geomorphological processes interacting to form a complex mosaic of landforms and deposits. The use of visible near infrared reflectance is an ideal tool for characterizing and monitoring surface covers and substrates. The objective of this work was to use reflectance spectroscopy to identify spectral characteristics of surface covers related to different volcanic deposits in ice-free areas of Deception Island, South-Shetland Islands. A site specific spectral library containing 220 reference spectra was compiled. Image-derived spectra from multispectral satellite data were easily labeled using the reference spectra. A preliminary distribution has distinguished five different deposit types over the entire area of Deception Island.
关键词： Reflectance spectra,spectral library,volcanic deposits,multispectral,geomorphology,South Shetland Islands
更新于2025-09-23 15:23:52
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Resonance reflection of light by ordered silicon nanopillar arrays with the vertical p-n junction
摘要： Silicon nanopillar (Si NP) arrays with the axial p-n junction were formed and investigated. A method to fabricate Si NP ordered arrays by means of electron beam lithography using the negative electron resist and reactive ion etching is presented. The effect of strong resonance light scattering – change of the color of separate Si NPs - was demonstrated. One or several minima were registered in the measured reflection spectra. Thereat, the position of reflection minimum was changed with a change in Si NP diameter. A shift of the minimum position towards the longer wavelength spectral region with an increase in Si NP diameter was observed. A shift of the position of minima to the shorter wavelength spectral region with a decrease in Si NP pitch in microarrays with the same Si NP diameter was observed. The quantitative divergence in the position of reflection minima in Si NPs with calculated dependencies for Mie resonances was found. High photosensitivity of Si NP arrays with axial p-n junction to visible and near IR light was discovered. So, these structures may be used for selective photonic sensors.
关键词： reflectance spectra,silicon nanopillars,electrophysical properties,reactive ion etching,electron beam lithography
更新于2025-09-23 15:23:52
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Infrared Spectroscopy on Electronic Structures of Platinum-group Metal Pernitrides MN2 (M = Ru, Rh, Ir, and Pt)
摘要： The electronic structures of platinum-group metal pernitrides MN2 (M = Ru, Rh, Ir, and Pt) were investigated via synchrotron radiation infrared spectroscopy and first-principles calculations. Measured reflectance spectra of marcasite-type RuN2 and RhN2 showed Drude-like responses, approaching 1 as the photon energy was decreased, whereas reflectance of arsenopyrite-type IrN2 and pyrite-type PtN2 became ~0.3 in the low photon energy region with a few features. These findings agreed well with the predictions of the metallic nature of marcasite-type RuN2 and RhN2 and the semiconducting properties of arsenopyrite-type IrN2 and pyrite-type PtN2, respectively. The measured reflectance spectra were also reasonably consistent with the calculated optical responses. The band gaps of IrN2 and PtN2 were estimated to be 0.8 and 2.1 eV, respectively, via first-principles calculation with a modified Becke–Johnson (MBJ) potential for the exchange potential.
关键词： first-principles calculation,platinum-group metal pernitride,infrared reflectance spectra,valence band electronic structure
更新于2025-09-23 15:22:29
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The application of proximal visible and near-infrared spectroscopy to estimate soil organic matter on the Triffa Plain of Morocco
摘要： Soil organic matter (SOM) is a fundamental soil constituent. The estimation of this parameter in the laboratory using the classical method is complex time-consuming and requires the use of chemical reagents. The objectives of this study were to assess the accuracy of two laboratory measurement setups of the VIS-NIR spectroscopy in estimating SOM content and determine the important spectral bands in the SOM estimation model. A total of 115 soil samples were collected from the non-root zone (0-20 cm) of soil in the study area of the Triffa Plain and then analysed for SOM in the laboratory by the Walkley–Black method. The reflectance spectra of soil samples were measured by two protocols, Contact Probe (CP) and Pistol Grip (PG)) of the ASD spectroradiometer (350-2500 nm) in the laboratory. Partial least squares regression (PLSR) was used to develop the prediction models. The results of coefficient of determination (R2) and the root mean square error (RMSE) showed that the pistol grip offers reasonable accuracy with an R2 = 0.93 and RMSE = 0.13 compared to the contact probe protocol with an R2 = 0.85 and RMSE = 0.19. The near-Infrared range were more accurate than those in the visible range for predicting SOM using the both setups (CP and PG). The significant wavelengths contributing to the prediction of SOM for (PG) setup were at: 424, 597, 1432, 1484, 1830 ,1920, 2200, 2357 and 2430 nm, while were at 433, 587, 1380, 1431, 1929, 2200 and 2345 nm for (CP) setup.
关键词： soil organic matter,SOM analysis.,VIS-NIR spectroscopy,reflectance spectra,SOM estimation
更新于2025-09-23 15:21:01
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ZnO and TiO2 Nanostructured Dye sensitized Solar Photovoltaic Cell
摘要： The performance of nanostructured metal oxides (ZnO and TiO2) based dye sensitized solar cells (DSSC) were investigated. Natural dye, chlorophyll extracted from fresh spinach leaves, was used as sensitizer for fabrication of the cells. ZnO was synthesized by chemical bath deposition technique.The Field emission scanning electron microscopic (FESEM) images show hexagonal patterned ZnO nano-towers of 5 μm length and ~ 1 μm diameter. TiO2 was synthesized by sol-gel method.The FESEM images show that the TiO2 nano-rods of 2 μm length and ~ 300 nm diameter.TiO2 based DSSC was possessed better efficiency of 0.27% as compare to ZnO based DSSC of 0.13%.
关键词： Diffused Reflectance Spectra,Chlorophyll dye,Dye sensitized solar cells,Chemical and sol-gel synthesis
更新于2025-09-16 10:30:52
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Reflectance spectra characteristics from an SPR grating fabricated by nano-imprint lithography technique for biochemical nanosensor applications
摘要： In this paper, we report our research work on developing a Surface Plasmon Resonance (SPR) element with sub-micron (hundreds of nanometers) periodicity grating structure. This grating structure was fabricated by using a simple nano-imprint lithography technique from an organically siloxane polymers, which was then covered by nanometer thin gold layer. The formed grating structure was a very well defined square-shaped periodic structure. The measured reflectance spectra indicate the SPR wave excitation on this grating structure. For comparison, the simulations of reflectance spectra have been also carried out by using Rigorous Coupled-Wave Analysis (RCWA) method. The experimental results are in very good agreement with the simulation results.
关键词： biochemical nanosensor,SPR,grating,nano-imprint lithography,reflectance spectra
更新于2025-09-10 09:29:36
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The effect of TiO <sub/>2</sub> nanopigment on the optical properties of polyester fabric in UV–VIS–NIR regions
摘要： The particle size parameter is a key factor that affects radiative properties of nano-pigments, and consequently, pigments of the same type but different sizes represent different spectral performance. Therefore, current study dealt with a systematic experimental investigation on the effect of TiO2 pigmented coatings on spectral reflectance and color performance of white and colored polyester fabrics in UV, VIS, and NIR region of electromagnetic spectrum, with a special emphasis on VIS region. In order to accomplish this target, polyester fabrics were coated with TiO2 nanopigment with various concentrations and different diameters, and their reflectance spectra were measured using spectrophotometric method. Two-way analysis of variance (ANOVA) was utilized to investigate the significance of the effect of TiO2 nanopigment on the color performance of coated fabrics. According to experimental observations, an organized color shift appears in color coordinate of fabrics coated with TiO2 nanopigment of various sizes. Moreover, although TiO2 nanopigment with 35 nm diameter has the most significant impact on short wavelength region (UV region), the effect of pigment with 250 nm diameter is more noticeable on NIR region as long wavelength region.
关键词： nanopigment,polyester fabric,reflectance spectra,optical property,titanium dioxide
更新于2025-09-04 15:30:14