Search results for "FTIR"

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…

OH-related Infrared Absorption Bands in Oxide Glasses

2005

We report the infrared activity, in the spectral region of the OH stretching modes, of different composite silicate glasses whose chemical composition is established by X-ray fluorescence measurements. The analysis of the absorption line profiles is made in terms of different spectral contributions, Gaussian in shape. The comparison with analogous spectra obtained in vitreous silica samples with impurity concentrations < 100 part per million moles is evidence of the effects of the different oxides on the vibrational properties of the OH groups. In particular, for oxide glasses a red shift of the composite band at about 3670 cm(-1), assigned to the OH stretching modes of free Si-OH groups an…

Lysozyme Aggregation Driven by Unfolding: the Role of Metal Ions

2007

Reaction products and pathways in the selective oxidation of C-2-C-4 alkanes on MoVTeNb mixed oxide catalysts

2010

[EN] The catalytic properties of MoVTeNbO catalysts during the selective oxidation of short chain alkanes and olefins (C-2-C-4) have been comparatively studied The main reaction products have been ethylene from ethane acrylic acid from propane maim anhydride from n-butane and methacrolein from isobutane FTIR studies of the adsorption of the main reaction products i e olefins and aldehydes over MoVTeNbO catalyst has been carried out Accordingly the reaction pathway is explained on the basis of the characteristics of the alkane fed the stability and reactivity of both the intermediates and the reaction products and the nature of the catalytic sites involved in each reaction (C) 2010 Elsevier …

Decoding vibrational states of Concanavalin A amyloid fibrils.

2015

International audience; Amyloid and amyloid-like fibrils are a general class of protein aggregates and represent a central topic in life sciences for their involvement in several neurodegenerative disorders and their unique mechanical and supramolecular morphological properties. Both their biological role and their physical properties, including their high mechanical stability and thermodynamic inertia, are related to the structural arrangement of proteins in the aggregates at molecular level. Significant variations may exist in the supramolecular organization of the commonly termed cross-β structure that constitutes the amyloid core. In this context, a fine knowledge of the structural deta…

Quantification of minerals from ATR-FTIR spectra with spectral interferences using the MRC method.

2017

A method for quantifying the individual components of mineral samples based on attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR) is described, extending the constant ratio (CR) method to analytes absorbing in a common range of wavenumbers. Absorbance values in the spectral region where the analytes absorb relative to the absorbance of an internal standard absorbing at a wavenumber where the analytes do not absorb, permits the quantification of N analytes using measurements at N fixed wavenumbers. The method was tested for mixtures of albite, orthoclase, kaolin and quartz.

Home-prepared anatase, rutile, and brookite TiO2 for selective photocatalytic oxidation of 4-methoxybenzyl alcohol in water: reactivity and ATR-FTIR …

2009

5th European Meeting on Solar Chemistry and Photocatalysis -- OCT 04-08, 2008 -- Palermo, ITALY

Bone diagenesis of archaeological human remains from Apulia (Italy) investigated by ATR-FTIR and XRF spectroscopy

2023

The analysis of the organic and mineral content of biological samples allows to define post-mortem alterations and the preservation status of ancient human remains. Here, we report a physical-chemical characterization of bone specimens from some skeletal remains found in Apulia (Italy) dating back to the prehistoric, classic-hellenistic, and medieval periods. Specific infrared band ratios from Attenuated Total Reflectance-Fourier Transform InfraRed and X-ray fluorescence spectroscopies were considered to evaluate the extent of the diagenetic process and the elemental composition of bone.Physical-chemical post-mortem transformations were related to the soil composition and specificity of tis…

Multi-analytical study of the medieval wall paintings from the rupestrian church Grotta del Crocifisso at Lentini (eastern Sicily): new evidence of t…

2022

AbstractThis study presents the results of the examination and characterisation of the wall paintings that decorate the rupestrian church named Grotta del Crocifisso, which is located in the territory of Lentini (eastern Sicily, few tens of kilometres from Catania and Syracuse). The earliest mural paintings in the church date back to the twelfth century AD. A multi-analytical approach was adopted for the characterisation of stone materials, secondary degradation products, and pigments. For this purpose, the following techniques were used: reflected light microscopy (RLM), polarised light microscopy on thin sections (PLM), X-ray powder diffraction (XRPD), mercury intrusion porosimetry (MIP),…

Spectroscopic analysis used to uncover the original paint colour of the Helsinki Government Palace tower clock faces

2016

The paint stratigraphy of the two clock faces from the tower clock of the Government Palace in Helsinki (Finland) was analysed in order to determine their original colour before restoration works. Paint cross-section samples from both clock faces were analysed by confocal Raman microscopy and scanning electron microscopy coupled to an energy dispersive X-ray spectrometer (SEM-EDS). The results revealed the complex superimposition of paint layers applied over the original black colour. FTIR/ATR analyses proved that the original paint was prepared with linseed oil-resin media. Most likely not all of the different layer colours were visible. Some of the layers were likely to have been a primer…