Search results for "Raman spectroscopy."
showing 10 items of 790 documents
"Identification of mixed bromidochloridotellurate anions in disordered crystal structures of (bdmim)2[TeX2Y4] (X, Y = Br, Cl; bdmim = 1-butyl-2,3-dim…
2013
Abstract The discrete mixed [TeBrxCl6−x]2− anions in their disordered crystal structures have been identified by using the phases prepared by the reaction of 1-butyl-2,3-dimethylimidazolium halogenides (bdmim)X with tellurium tetrahalogenides TeX4 (X = Cl, Br) as examples. Homoleptic (bdmim)2[TeX6] [X = Cl (1), Br (2)] and mixed (bdmim)2[TeBr2Cl4] (3), and (bdmim)2[TeBr4Cl2] (4) are formed depending on the choice of the reagents, and their crystal structures have been determined by single-crystal X-ray diffraction. The coordination environments of tellurium in all hexahalogenidotellurates are almost octahedral. Because of the crystallographic disorder, the mixed [TeBr2Cl4]2− and [TeBr4Cl2]2…
Lateral Fusion of Chemical Vapor Deposited N = 5 Armchair Graphene Nanoribbons
2017
Bottom-up synthesis of low-bandgap graphene nanoribbons with various widths is of great importance for their applications in electronic and optoelectronic devices. Here we demonstrate a synthesis of N = 5 armchair graphene nanoribbons (5-AGNRs) and their lateral fusion into wider AGNRs, by a chemical vapor deposition method. The efficient formation of 10- and 15- AGNRs is revealed by a combination of different spectroscopic methods, including Raman and UV−visnear-infrared spectroscopy as well as by scanning tunneling microscopy. The degree of fusion and thus the optical and electronic properties of the resulting GNRs can be controlled by the annealing temperature, providing GNR films with o…
High photodegradation and antibacterial activity of BN–Ag/TiO 2 composite nanofibers under visible light
2018
To develop material with good photocatalytic properties for organic compound degradation and bacterial removal, we produced Ag/TiO2 and BN–Ag/TiO2 composite nanofibers that included controlled amounts of boron nitride (BN) nanosheets and silver (Ag). After annealing at 500 °C under air, we used scanning electron microscopy, transmission electron microscopy, Brunauer–Emmet–Teller analysis, X-ray diffraction, energy-dispersive X-ray spectroscopy, Raman spectroscopy, UV-visible reflectance spectroscopy and room temperature photoluminescence to investigate the morphological, structural and optical properties of all samples. The photocatalytic tests using methylene blue under visible light, in r…
Ruthenium Oxide Nanotubes Via Template Electrosynthesis
2011
Ruthenium oxide nanotubes were fabricated by a single-step galvanostatic deposition using porous anodic alumina membrane as template. For the electrodeposition process, we used a electrochemical cell specifically designed in order to employ only 0.5 ml of 0.02 M RuCl3•xH2O solution. The deposition from a very small volume was specifically addressed owing to the high cost of ruthenium compounds, which could be of some relevance from an applicative point of view. Several techniques were used to characterize the samples prior to and after thermal treatment, which was carried out at different temperatures in order to study the crystallization process of the deposit. Raman spectroscopy of as-dep…
Micro-Raman spectroscopy of pigments contained in different calcium carbonate polymorphs from freshwater cultured pearls
2008
The metastable calcium carbonate polymorph vaterite has recently been found to occur commonly in freshwater cultured pearls from Japan and China. Organic pigment molecules in these vaterite regions of freshwater cultured pearls were analysed by resonance and near-resonance micro-Raman spectroscopy, in single spectra and in mapping modes and are compared with their aragonitic counterparts. Four different excitation wavelengths (487.9, 514.5, 532.2 and 632.8 nm) were used, resulting in differential increase of resolution for the pigments. Although vaterite areas were always lightly coloured (light yellow, light brown or white), ten different pigments were identified and a single colour is for…
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),…
Electrochemical Fingerprint of Archeological Lead Silicate Glasses Using the Voltammetry of Microparticles Approach
2016
9 págs.; 14 figs.; 1 tab.
Non-Invasive Investigation of Pigments of Wall Painting in S. Maria Delle Palate di Tusa (Messina, Italy)
2019
The characterization of materials used in the archaeological field needs an experimental approach in order to avoid the destruction or perturbation of artworks. In order to afford this purpose, a multi-analytical spectroscopic approach is regularly used. We combined non-invasive analysis by using handheld spectroscopic instrumentations (mainly XRF and Raman spectrometers) in order to characterize the wall painting preserved in the church of S. Maria delle Palate at Halaesa Arconidea archeological site (Tusa, Messina, Italy). The aim of the work is the characterization of the nature of pigments used for the realization of the wall painting. The wall painting, probably representing St. Franci…
<title>Electrochromism in oxyfluoride thin films</title>
1994
Oxyfluoride films based on W and Ti were prepared by reactive sputtering in plasmas containing O2 + CF4. The deposition rate was large, particularly when chemical sputtering was promoted by heating the target. The films could show large charge insertion/extraction, high coloration efficiency, and good cycling durability.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Raman spectroscopy and high-overtone driven isomerization of glyoxylic acid in solid argon
2013
High-overtone induced chemistry of glyoxylic acid isolated in a low-temperature argon matrix was investigated using Raman spectroscopy. The Raman spectra of two most stable conformers of glyoxylic acid are presented. Upon excitation in high overtone vibrational bands by 532 nm irradiation of the lowest energy conformer most abundant in neat deposited sample, the isomerization of glyoxylic acid was observed. The process most plausible proceeds via absorption into the fifth vibrational overtone state of the OH group or its combination with the torsional vibrational transition. The assignment of the fundamental vibrational spectra was assisted by quantum chemical harmonic and anharmonic vibrat…