Search results for " Infrared"
showing 10 items of 945 documents
Density Functional Theory Calculated Raman Spectra of Ergocalciferol (Vitamin D2) and Cholecalciferol (D3)
2021
Density functional theory (DFT)-calculated Infrared and Raman spectra of Vitamin D2 and D3 are presented. The calculated results are compared with each other and with available experimental data. Applicability of Raman spectra for non-invasive optical Vitamin D sensors is discussed.
Isotopically (δ13C and δ18O) heavy volcanic plumes from Central Andean volcanoes: a field study
2017
International audience; Stable isotopes of carbon and oxygen in volcanic gases are key tracers of volatile transfer between Earth's interior and atmosphere. Although important, these data are available for few volcanoes because they have traditionally been difficult to obtain and are usually measured on gas samples collected from fumaroles. We present new field measurements of bulk plume composition and stable isotopes (δ13CCO2 and δ18OH2O+CO2) carried out at three northern Chilean volcanoes using MultiGAS and isotope ratio infrared spectroscopy. Carbon and oxygen in magmatic gas plumes of Lastarria and Isluga volcanoes have δ13C in CO2 of +0.76‰ to +0.77‰ (VPDB), similar to slab carbonate;…
Hot-spot detection and characterization of strombolian activity from MODIS infrared data
2014
Identifying and characterizing strombolian activity from space is a challenging task for satellite-based infrared systems. Stromboli volcano is a natural laboratory that offers a unique opportunity for refining thermal remote-sensing applications that involve transient phenomena and small to moderate hot-spots. A new simple and fast algorithm gave us the opportunity to revisit the MODIS-derived thermal output at Stromboli volcano over the last 13 years. The new algorithm includes both night-time and daytime data and shows high performance with the detection of small-amplitude thermal anomalies ( 1000 MW). The ...
On-line database of voltammetric data of immobilized particles for identifying pigments and minerals in archaeometry, conservation and restoration (E…
2016
[EN] A web-based database of voltammograms is presented for characterizing artists' pigments and corrosion products of ceramic, stone and metal objects by means of the voltammetry of immobilized particles methodology. Description of the website and the database is provided. Voltammograms are, in most cases, accompanied by scanning electron microphotographs, X-ray spectra, infrared spectra acquired in attenuated total reflectance Fourier transform infrared spectroscopy mode (ATR-FTIR) and diffuse reflectance spectra in the UV-Vis-region. For illustrating the usefulness of the database two case studies involving identification of pigments and a case study describing deterioration of an archae…
A FTIR study on low hydration saccharide amorphous matrices: Thermal behaviour of the Water Association Band
2011
Abstract We report a study on the thermal behaviour of the infrared Water Association Band (WAB) in dry binary saccharide–water systems (containing trehalose, sucrose, maltose, and raffinose). This is a follow-up of preceding studies on analogous carboxymyoglobin-saccharide–water ternary systems, which pointed out a mutual protein-matrix influence (coupling). A comparison between binary and ternary systems, for all the saccharides studied, evidences a reduction in the residual water content in the latter and, except for trehalose, a sizable modification in the thermal behaviour, which is discussed in terms of structure and hydrogen bonding properties of the sugars. The study allowed us also…
Comparison of field emissivities with laboratory measurements and ASTER data
2008
Surface emissivity in the thermal infrared (TIR) region is an important parameter for determining the land surface temperature from remote sensing measurements. This work compares the emissivities measured by different field methods (the Box method and the Temperature and Emissivity Separation, TES, algorithm) as well as emissivity data from ASTER scenes and the spectra obtained from the ASTER Spectral Library. The study was performed with a field radiometer having TIR bands with central wavelengths at 11.3 μm, 10.6 μm, 9.1 μm, 8.7 μm and 8.4 μm, similar to the ASTER TIR bands. The measurements were made at two sites in southern New Mexico. The first was in the White Sands National Monument…
Bio-inspired consolidants derived from crystalline nanocellulose for decayed wood
2018
Abstract Novel bio-inspired materials derived from crystalline nanocellulose (CNC) have been tested as wood consolidants. A suspension of CNC, produced by acid hydrolysis of cellulose and used as such or mixed with lignin and/or siloxane derivatives (PDMS), was applied on rotted wood samples of Norway spruce. X-Ray diffraction analysis on CNC powder showed high crystallinity index. Dynamic light scattering (DLS) measurement indicated a nearly uniform particle size distribution with an average hydrodynamic diameter for pure CNC smaller than that in the mixtures. Raman and FTIR spectroscopies suggested interactions between lignin, PDMS and CNC components. The storage modulus of wood samples, …
On the impact of side methyl groups on the structure and vibrational properties of β-carotenoids. The case of butadiene and isoprene
2021
Abstract Theoretical consideration about the impact of methyl groups on the structure and vibrational properties of β-carotenoids, using medium size molecules of trans-butadiene and trans-isoprene, are reported. Density functional theory (DFT) calculations with correlation-consistent and polarization-consistent basis sets were applied to trans-1,3-butadiene and trans-isoprene as the smallest building bricks of β-carotenoids. Their structure and harmonic vibrations were estimated in the complete basis set limit (CBS) using the non-linear least square fit. Optimized geometries and harmonic frequencies, obtained with B3LYP and BLYP density functionals and large basis sets, were favorably repro…
Near-infrared luminescence of isolated and exchange-coupled Ni2+ ions in NicMg1−cO solid solutions
1997
NicMg1−cO (0.01 ⩽ c ⩽ 1) solid solutions were studied by near-infrared luminescence, optical absorption and X-ray absorption spectroscopies. It was found that Ni2+ ions form at c < 0.2 the exchange-coupled pairs, strongly bound via 90 ° super-exchange interactions, and are displaced at c ⩽ 0.6 to the ‘off-center’ positions. This explains the origin of the zero-phonon line splitting observed in the optical absorption and luminescence spectra. It was also found that the effective energy transfer from the single Ni2+ ions to the exchange-coupled Ni2+-Ni2+ pairs occurs at temperatures below 40 K.
Investigation of phthalocyanine crystals exposed to NO2 ambient gas
2002
Crystals of free base phthalocyanine (H2pc) and its unsubstituted metal derivatives Mpc (where M=Ni, Cu, Zn, Pb, and pc=C32H16N8 2−=phthalocyanine ligand) were examined after being exposed to NO2 ambient gas. Scanning electron microscopy (SEM) supported by X-ray microprobe analysis (EDAX), UV–Vis and FTIR spectroscopy as well as X-ray powder diffractometry (XRD) were applied to study the crystals chemistry and surface morphology. The NO2 molecules were found to penetrate the crystal unit which led to the breakdown of the phthalocyanine macrocycle. The surface of the doped crystals has been scaled and covered by a layer composed predominantly of phthalimide. Despite vacuum desorption, it has…