Search results for "SPECTRA"
showing 10 items of 3542 documents
Line mixing in the ν1 and 2ν2 isotropic Raman Q-branch of CO2 perturbed by argon and helium
1999
0021-9606; The shapes of the ν1 and 2ν2 isotropic Raman Q-branch of CO2 perturbed by argon and helium have been measured by Stimulated Raman Spectroscopy (SRS) or coherent anti-Stokes Raman Spectroscopy (CARS) techniques. The data have been successfully analyzed with an energy corrected sudden (ECS) approximation model based on basic rates determined independently. Finally comparison of the present data with time resolved double resonance experiments allows us to discuss the physical origin of the two empirical constants which account for the shift and broadening of the branch due to vibrational effects. (C) 1999 American Institute of Physics. [S0021-9606(99)00344-X].
The Pyridyl Functional Groups Guide the Formation of Pd Nanoparticles Inside A Porous Poly(4-Vinyl-Pyridine)
2015
The reactivity of palladium acetate inside a poly(4-vinylpyridine-co-divinylbenzene) polymer is strongly influenced by the establishment of interaction between the Pd precursor and the pyridyl functional group in the polymer. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and simultaneous X-ray absorption near edge structure (XANES) and small angle X-ray scattering (SAXS) techniques have been applied to monitor the reactivity of palladium acetate in the presence of H-2 and CO as a function of temperature. H-2 reduces palladium acetate to Pd nanoparticles and acetic acid. The pyridyl groups in the polymer play a vital role both in stabilizing the formed acetic acid, thu…
Studies in organic mass spectrometry. Part 20: a hidden ortho effect in the electron ionisation mass spectra of some 2′-alkyl substituted 2-and 3-thi…
1996
The electron-ionisation-induced amide-bond cleavage of some 2′-methyl- and 2′-ethyl-substituted 2- and 3-thiophenecarboxanilides, which yields formally anilylium ions having relative intensities apparently in contrast with the Stevenson‐Audier rule, has been investigated by mass-analysed ion kinetic energy (MIKE) spectrometry and compared to that of the 3 ′- and 4′-isomers. It has been shown that, in the case of the 2 ′-methyl and 2′-ethyl derivatives, the amide-bond cleavage is anchimerically assisted through the hidden migration of a benzyl hydrogen to the nitrogen. Analysis of the MIKE and collision-induced decomposition (CID) MIKE spectra of model compounds indicates that this cryptic o…
Modeling the mixed-morphology supernova remnant IC 443. Origin of its complex morphology and X-ray emission
2020
The morphology and the distribution of material observed in SNRs reflect the interaction of the SN blast wave with the ambient environment, the physical processes associated with the SN explosion and the internal structure of the progenitor star. IC 443 is a MM SNR located in a quite complex environment: it interacts with a molecular cloud in the NW and SE areas and with an atomic cloud in the NE. In this work we aim at investigating the origin of the complex morphology and multi-thermal X-ray emission observed in SNR IC 443, through the study of the effect of the inhomogeneous ambient medium in shaping its observed structure, and the exploration of the main parameters characterizing the re…
Analysis of Hyperspectral Images of Citrus Fruits
2010
Publisher Summary Some of the most important aspects that need to be taken into consideration when developing a hyperspectral inspection system for citrus include the geometry of the fruit, the emission spectrum of the lighting source, and their interaction. Because many citrus fruits are almost spherical, each point of their surface reflects the electromagnetic radiation differently toward the camera. This causes a gradual darkening of the image especially the further pixels from the light source, which is a phenomenon that must be artificially corrected. In addition, the variation of the efficiency of the filters with the wavelength should be also taken into consideration to enable the ap…
Optimization of image parameters using a hyperspectral library application to soil identification and moisture estimation
2009
The growing number of sensors raises questions about the image parameters required for the application, soil identification and moisture estimation. Hyperspectral images are also known to contain highly redundant information. Hence not all the spectral bands are needed for the satisfactory classification of the soil types. Hence, the work was aimed at obtaining these optimal spectral bands for identifying the soil types and to use these spectral bands to estimate the moisture content of the soils using the method proposed by Whiting et.al.
Denoising AVIRIS-NG Data for Generation of New Chlorophyll Indices
2021
The availability of Airborne Visible and Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) data has enormous possibilities for quantification of Leaf Chlorophyll Content (LCC). The present study used the AVIRIS-NG campaign site of Western India for generation and validation of new chlorophyll indices by denoising the AVIRIS-NG data. For validation, concurrent to AVIRIS-NG flight overpass, field samplings were performed. The acquired AVIRIS-NG was subjected to Spectral Angle Mapper (SAM) classifier for discriminating the crop types. Three smoothing techniques i.e., Fast-Fourier Transform (FFT), Mean and Savitzky-Golay filters were evaluated for their denoising capability. Raw and fil…
Comparative study of multi-2D, Full 3D and hybrid strategies for multi/hyperspectral image compression
2009
In this paper, we investigate appropriate strategies for multi/hyperspectral image compression. In particular, we compare the classic multi-2D compression strategy and two different implementations of 3D strategies (Full 3D and hybrid). All strategies are combined with a PCA decorrelation stage to optimize performance. For multi-2D and hybrid strategies, we propose a weighted version of PCA. Finally, for consistent evaluation, we propose a larger comparison framework than the conventionally used PSNR. The results are significant and show the weaknesses and strengths of each strategy.
A Database of Spectral Filter Array Images that Combine Visible and NIR
2017
International audience; Spectral filter array emerges as a multispectral imaging technology, which could benefit several applications. Although several instantiations are prototyped and commercialized, there are yet only a few raw data available that could serve research and help to evaluate and design adequate related image processing and algorithms. This document presents a freely available spectral filter array database of images that combine visible and near infra-red information.
Modelling spatial and spectral systematic noise patterns on CHRIS/PROBA hyperspectral data
2006
In addition to typical random noise, remote sensing hyperspectral images are generally affected by non-periodic partially deterministic disturbance patterns due to the image formation process and characterized by a high degree of spatial and spectral coherence. This paper presents a new technique that faces the problem of removing the spatial coherent noise known as vertical stripping (VS) usually found in images acquired by push-broom sensors, in particular for the Compact High Resolution Imaging Spectrometer (CHRIS). The correction is based on the hypothesis that the vertical disturbance presents higher spatial frequencies than the surface radiance. The proposed method introduces a way to…