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Raman spectroscopy

About: Raman spectroscopy is a research topic. Over the lifetime, 122605 publications have been published within this topic receiving 2891083 citations. The topic is also known as: Raman Spectrum Analysis & spectrum Analysis, Raman.


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Journal ArticleDOI
TL;DR: In this paper, the surface phase structure of TiO2 nanoparticles calcined at different temperatures was studied using FT-IR spectroscopy with CO and CO2 as probe molecules and the results showed that the surface Lewis acidity of anatase phase is stronger than that of rutile phase.
Abstract: Surface phases of TiO2 nanoparticles (30 ∼ 200 nm) were studied by UV Raman spectroscopy and FT-IR spectroscopy with CO and CO2 as probe molecules. UV Raman spectroscopy can differentiate the surface phase structure of TiO2 calcined at different temperatures. IR spectra of adsorbed CO and CO2 on TiO2 calcined at different temperatures are in good agreement with the results from UV Raman spectra. IR results evidently confirm that UV Raman spectroscopy is a surface-sensitive technique for TiO2. Both UV Raman and IR spectra indicate that the crystalline phase of TiO2 in the surface region is usually different from that in the bulk which is characterized by XRD. CO is weakly adsorbed on Ti4+ ions of anatase phase but is hardly adsorbed on those of rutile phase at room temperature. Adsorbed CO2 on anatase phase produces mainly bidentate carbonate, while on rutile phase produces mainly bicarbonate species. These results suggest that the surface Lewis acidity of anatase phase is stronger than that of rutile phas...

278 citations

Journal ArticleDOI
TL;DR: In this article, a facial one-pot hydrothermal method was used to load Fe2O3 supported on nitrogen-doped graphene hydrogel and obtain a specific capacitance as high as 618 F g/1 at discharge current density of 0.5 A g/g/1.
Abstract: Fe2O3 supported on nitrogen-doped graphene (Fe2O3/N-rGO) hydrogel was prepared by a facial one-pot hydrothermal method. The efficient Fe2O3 loading and nitrogen doping of graphene was realized with this method. The morphology and structure of the samples were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, thermal gravimetric analysis, Raman spectra, X-ray diffraction, and nitrogen isothermal adsorption–desorption. The chemical environment of the surface composition of the samples was recorded by X-ray photoelectron spectroscopy. The electrochemical performance was tested with a three-electrode system in the aqueous electrolyte of 1 M KOH. The electrochemical measurement demonstrated that Fe2O3/N-rGO shows a specific capacitance as high as 618 F g–1 at a discharge current density of 0.5 A g–1. Even at the current density of 10 A g–1, the specific capacitance is still as high as 350 F g–1. After 5000 cycles, the capacity retention is still maintained at 56.7%.

278 citations

Journal ArticleDOI
TL;DR: In this article, the structural details of doped polyacetylene (a highly conducting organic polymer) were studied using optical absorption, Raman, and infrared spectra of polyacetylenes.
Abstract: In order to elucidate the structural details of doped polyacetylene (a highly conducting organic polymer), the optical absorption, Raman, and infrared spectra of not only trans‐(CH)x doped with iodine, AsF5, and SO3 but also β‐carotene doped with iodine and SO3 were studied. The infrared spectra of two kinds of isotopically substituted polyacetylenes (CD)x and (13CH)x doped with iodine were also observed. Analysis of the experimental results shows that upon doping each of the four vibrational branches (ν1–ν4) in the 1600–900 cm−1 region of a polyene chain splits into two groups, namely, the higher frequency group and the lower frequency one. The former group consists of the ’’gerade’’ vibrations of polyene parts which are not directly attacked by dopants but are perturbed along the chain, whereas the latter is made up of the ’’ungerade’’ vibrations of the positively charged polyene part with the doped site at its center. The Raman bands in the higher‐frequency group of ν1 (mainly the C=C stretching mode) ...

278 citations

Journal ArticleDOI
TL;DR: In this article, the authors used a simple and a facile hydrothermal technique to fabricate NO 2 gas sensor using thin films of tungsten oxide (WO 3 ) grown directly on to a soda-lime glass substrate without assistance of any seed layer.
Abstract: Gas sensors based on a chemiresistive metal oxide semiconductor are widely used including nitrogen dioxide (NO 2 ) at a moderate temperature. In this work efforts are taken to fabricate NO 2 gas sensor using thin films of tungsten oxide (WO 3 ) grown directly on to a soda-lime glass substrate without assistance of any seed layer by a simple and a facile hydrothermal technique. As per our knowledge, the deposition of nanostructured WO 3 thin films without assistance of any seed layer on the glass substrate was rarely reported. The WO 3 thin film samples were synthesized at various deposition times ranging from 3 h to 7 h and were characterized by X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV–vis spectroscopy and Brunauer-Emmett-Teller techniques. The surface morphological and structural characterization showed the two dimensional (2D) nanoplate-like structure of as synthesized WO 3 thin films with plate thickness ranging from 90 to 150 nm and had an orthorhombic structure, respectively. Moreover, the 2D nanoplates of WO 3 exhibited a gas response ∼10 for 5 ppm for toxic NO 2 gas at relatively low operating temperature. The new synthesis route and sensing behavior of as synthesized WO 3 nanoplates revealed a promising candidate for the fabrication of the cost effective gas sensors.

278 citations

Journal ArticleDOI
TL;DR: In this article, a systematic study of the shift and linewidth of the Eg Raman peak at 144 cm−1 of anatase TiO2 nanopowders, produced by a flame aerosol technique, is presented.
Abstract: A systematic study of the shift and linewidth of the Eg Raman peak at 144cm−1 of anatase TiO2 nanopowders, produced by a flame aerosol technique, is here presented. The analysis was performed as a function of the crystal domain size and of the degree of oxidation. In the nanopowders, a clear contribution of the stoichiometry defects to the peak shift was evidenced, while the peak width seems to be less affected by the oxygen content. The Raman peak behavior due to size reduction has been interpreted in the framework of a phonon quantum confinement model. A critical review of the different approaches to this model, adopted in the literature to explain the behavior of the anatase Raman spectra as a function of the domain size, is presented. In particular, the hypothesis of a three-dimensional isotropic model for the dispersion relations is discussed. This analysis evidences general limits in the application of the phonon confinement model to the study and characterization of nanoparticles and nanostructured...

278 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20235,220
202210,775
20214,240
20204,764
20194,957
20184,893