Search results for " infrared"
showing 10 items of 945 documents
Contribution à l'étude des liaisons optiques atmosphériques : propagation, disponibilité et fiabilité.
2005
In this work we study the fog attenuation in the visible and infrared spectral band related to Free Space Optics (FSO). Based on the Mie scattering theory, fog extinction coefficients for different particle size distributions as a function of wavelength were derived. A simple analytical model allowing the prediction of atmospheric transmission for the 0.69 - 1.55 µm spectral band was developed. This model is valid for advection and convection fog and for visibility range between 50 to 1000 m. This model, implemented into software developed at FT R&D, allows the prediction of the Quality of Service of FSO links. Finally, we performed an experimental study to compare the fog effect on two FSO…
Study of water adsorption and capillary bridge formation for SiO(2) nanoparticle layers by means of a combined in situ FT-IR reflection spectroscopy …
2014
Water adsorption and capillary bridge formation within a layer of SiO2-nanoparticles were studied in situ by means of a combination of quartz crystal microbalance (QCM-D) with dissipation analysis and Fourier transformation infrared reflection absorption spectroscopy (FT-IRRAS). FT-IR data were employed to distinguish the “ice-like” and “liquid-like” contributions and to support the analysis of the QCM-D data concerning mass change and dissipation. Combined measurements show that for SiO2-nanoparticles with a diameter of about 250 nm, the formation of two adsorbed monolayers of water as well as bulk water leads to a rather linear increase in the dissipation for relative humidity values of u…
Irradiation effects on the OH-related infrared absorption band in synthetic wet silica.
2007
The effects of b-irradiation on the OH-related infrared (IR) absorption band in synthetic wet silica samples have been investigated by Fourier transform infrared spectroscopy. Depending on the accumulated doses, b-irradiation affects different zones of the IR composite band at about 3670 cm 1 , assigned to the OH stretching modes of silanol groups. These modifications are independent of the original OH content. The results are discussed considering possible radiation-induced changes of the silanol bonding configuration and of the glass network. These are monitored by revealing the IR band a 2260 cm 1 , which is related to the distribution of Si–O–Si bond angle. We have identified the existence of…
Iodine−Benzene Complex as a Candidate for a Real-Time Control of a Bimolecular Reaction. Spectroscopic Studies of the Properties of the 1:1 Complex I…
2009
The properties of the 1:1 iodine-benzene complex isolated in a solid Kr matrix at low temperatures have been studied using UV-vis absorption, FTIR, resonance Raman, and femtosecond coherent anti-Stokes Raman spectroscopy (fs-CARS). The use of all these techniques on similar samples provides a wide view on the spectroscopic properties of the complex and allows comparison and combination of the results from different methods. The results for the complex cover its structure, the changes in the iodine molecule's vibrational frequencies and electronic absorption spectrum upon complexation, and the dynamics of the complexed I(2) molecule on both ground and excited electronic states. In addition, …
Temperature effects on the IR absorption bands of hydroxyl and deuteroxyl groups in silica glass
2009
Abstract In this report we will show the changes of the band shape of the hydroxyl group (SiOH) infrared (IR) absorption band (∼3670 cm −1 ) in silica glass induced by lowering temperature in the range from 290 to 20 K. This band is considered as the overlap of several spectral components associated to the vibrational activity of hydroxyl groups in different bond configurations. By a suitable analysis of the experimental band profile in terms of different sub-bands, we studied the thermal evolution of each component and we reconsidered their assignations. For comparison we examined the SiOD absorption band (∼2710 cm −1 ) as a function of temperature as well. Our data can be interpreted as a…
Characterization of particle morphology of biochanin A molecularly imprinted polymers and their properties as a potential sorbent for solid-phase ext…
2014
Abstract Molecularly imprinted polymers (MIPs) with biochanin A as a template were obtained using a bulk polymerization with non-covalent imprinting approach. The polymers were prepared in acetonitrile as porogen, using ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The synthesis, with an application of 1′,1′-azobis(cyclohexanecarbonitrile) (ACHN) as an initiator, has been performed thermally. During the synthesis process the effect of different functional monomers such as methacrylic acid (MAA), acrylamide (AA) and 4-vinylpyridine (4-VP) was investigated. The application of nitrogen sorption porosimetry, scanning electron microscopy (SEM), and Fourier transform infrared spec…
Coordination properties of adenosine-5'-monophosphate and related ligands towards Me2Sn(IV)2+ in aqueous solution.
2002
Abstract The coordination of Me 2 Sn(IV) 2+ to adenosine-5′-monophosphate (AMP) and the related compounds d -ribose-5-phosphate (R5P), d -glucose-1-phosphate (G1P) and d -glucose-6-phosphate (G6P) in aqueous solution was investigated by means of potentiometric titration, and 1 H-, 31 P-NMR and Mossbauer spectroscopic methods in the pH range 2–11 ( I =0.1 M NaClO 4 , 298 K). The complex of AMP and Me 2 Sn(IV) 2+ precipitated at low pH was characterised by elemental analysis, FT-IR and Mossbauer spectroscopic methods. From a comparison of the p K values obtained in the presence and absence of metal ion and the stability constants for the different systems, the coordination of {N} is excluded,…
Noninvasive double confirmation of cocaine abuse.
2013
A double confirmation procedure, based on the combined application of Ion Mobility Spectrometry (IMS) and Infrared Spectroscopy (IR), has been developed for the noninvasive unambiguous identification of cocaine consume. The use of nasal mucus as a biological specimen for cocaine abuse confirmation has been proposed as an alternative to the use of blood and urine due to its noninvasive character and the presence of the parent compound instead of its metabolites. Sampling conditions, interferences caused by cutting agents and other substances, and limits of identification (LOI) and confirmation (LOC) have been deeply evaluated. The procedure combines the high sensitivity of the IMS to identif…
Analysis of ecstasy in oral fluid by ion mobility spectrometry and infrared spectroscopy after liquid-liquid extraction.
2014
We developed and evaluated two different strategies for determining abuse drugs based on (i) the analysis of saliva by ion mobility spectrometry (IMS) after thermal desorption and (ii) the joint use of IMS and infrared (IR) spectroscopy after liquid-liquid microextraction (LLME) to enable the sensitivity-enhanced detection and double confirmation of ecstasy (MDMA) abuse. Both strategies proved effective for the intended purpose. Analysing saliva by IMS after thermal desorption, which provides a limit of detection (LOD) of 160μgL(-1), requires adding 0.2M acetic acid to the sample and using the truncated negative second derivative of the ion mobility spectrum. The joint use of IMS and IR spe…
Efficacy of single-source rapid kV-switching dual-energy CT for characterization of non-uric acid renal stones: a prospective ex vivo study using ant…
2019
Purpose To investigate the accuracy of rapid kV-switching single-source dual-energy computed tomography (rsDECT) for prediction of classes of non-uric-acid stones. Materials and methods Non-uric-acid renal stones retrieved via percutaneous nephrolithotomy were prospectively collected between January 2017 and February 2018 in a single institution. Only stones >= 5 mm and with pure composition (i.e., >= 80% composed of one component) were included. Stone composition was determined using Fourier Transform Infrared Spectroscopy. The stones were scanned in 32-cm-wide anthropomorphic whole-body phantom using rsDECT. The effective atomic number (Zeff), the attenuation at 40 keV (HU40), 70 ke…