Search results for "RAMAN"
showing 10 items of 1328 documents
Orthorhombic boron oxide under pressure: in situ study by X-ray diffraction and Raman scattering
2016
High-pressure phase of boron oxide, orthorhombic \b{eta}-B2O3, has been studied in situ by synchrotron X-ray diffraction to 22 GPa and Raman scattering to 46 GPa at room temperature. The bulk modulus of \b{eta}-B2O3 has been found to be 169(3) GPa that is in good agreement with our ab initio calculations. Raman and IR spectra of \b{eta}-B2O3 have been measured at ambient pressure, all experimentally observed bands have been attributed to the theoretically calculated ones, and the mode assignment has been performed. Based on the data on Raman shift as a function of pressure, combined with equation-of-state data, the Gr\"uneisen parameters of all experimentally observed Raman bands have been …
Wavelength influence on nitrogen insertion into titanium by nanosecond pulsed laser irradiation in air
2013
Abstract We studied in this work the influence of the wavelength (532 vs. 1064 nm) on the insertion of nitrogen in titanium targets by surface laser treatments in air. The laser pulses were of 5 ns and the irradiance was lower than 25 × 10 12 W/m 2 . Results obtained using a frequency-doubled Nd:YAG laser at 532 nm were compared with those previously reported for laser treatments at 1064 nm. Nuclear reaction analysis and micro-Raman spectroscopy were used for determining the composition and the structure of the surface layers, respectively. Results showed the lower efficiency of irradiation at 532 nm for nitrogen insertion, which is possible only above threshold conditions depending on bot…
Resonant Raman characterisation of ultra-thin nano-protective carbon layers for magnetic storage devices
2003
Abstract Carbon thin films are very important as protective coatings for a wide range of applications such as magnetic storage devices. The key parameter of interest is the sp3 fraction, since it controls the mechanical properties of the film. Visible Raman spectroscopy is a very popular technique to determine the carbon bonding. However, the visible Raman spectra mainly depend on the configuration and clustering of the sp2 sites. This can result in the Raman spectra of different samples looking similar albeit having a different structure. Thus, visible Raman alone cannot be used to derive the sp3 content. Here we monitor the carbon bonding by using a combined study of Raman spectra taken a…
High-resolution Raman spectroscopy of the ν1 region and Raman-Raman double resonance spectroscopy of the 2ν1-ν 1 band of 32SF6 and 34SF 6. Determinat…
2004
The ν1 region of 32SF6 and 34SF6 has been studied by stimulated Raman spectroscopy. For both isotopomers, a detailed analysis has been performed. Several hot bands (ν1+ν6-ν6, ν1+2ν 6-2ν6, ν1+ν5-ν 5) have been taken into account to calculate synthetic spectra that satisfactorily reproduce the experimental data. These results, together with the previous studies of the other fundamental bands have allowed us to determine the equilibrium bond length of sulfur hexafluoride as r e=1.5560(1) Å, in very good agreement with recent ab initio calculations. The 2ν1-ν1 band has also been studied for both isotopomers by Raman-Raman double resonance spectroscopy and the resulting spectra have been analyze…
High-resolution stimulated Raman spectroscopy of O2
1992
Abstract The S S and O O branches of the fundamental vibrational band of molecular oxygen in its electronic ground state have been resolved for the first time in Raman spectroscopy. The spectra have been observed, at room temperature and low pressure, with a stimulated Raman scattering (S.R.S.) spectrometer including a multipass cell. From these accurate Raman data combined with microwave data, we have improved the values of the vibrational, rotational, spin-spin, and spin-rotation interactions constants in the v = 1 vibrational state. Moreover, Raman Q branches of the first and second hot-bands have been recorded, allowing us to determine a set of molecular parameters for the v = 2 and v =…
Resonance Raman of oxygen dangling bonds in amorphous silicon dioxide
2016
We investigate the origin of a resonance Raman band induced by ionizing radiation in amorphous silicon dioxide (silica glass), which can be detected under ultraviolet laser excitation. A silica sample, rich of oxygen-excess related defects, was prepared by treating some length of a pure-silica-core multimode fiber in an O2 atmosphere (at high temperature and pressure) and by irradiating it with X-rays at 10 MGy(SiO2) dose. A micro-Raman study revealed a gaussian band peaking at 896 cm−1 with a full width at half maximum of 32 cm−1, which could be detected by exciting the sample with the 325-nm line of a HeCd laser. This spectral feature is absent in the Raman spectra performed with the 442-…
Structural, electrical and optical properties of zinc‐iridium oxide thin films deposited by DC reactive magnetron sputtering
2014
ZnO-IrO2 thin films were deposited on glass by DC reactive magnetron sputtering at room tem-perature. Structural, electrical and optical properties were investigated as a function of iridium atomic concentra-tion in the films. XRD data shows that ZnO-IrO2 thin films are X-ray amorphous and Raman spectrum resembles the spectrum of IrO2, without any distinct features of wurtzite ZnO structure. The lowest film resistivity and the highest transmittance achieved in the present study were 1.4 × 10-3 Ωcm and 33% at 550 nm, respectively. However, resistivity and transmittance are inversely related to the iridium concentration in the films.
Growth of glass-embedded Cu nanoparticles: A low-frequency Raman scattering study
2012
International audience; Several populations of Cu spherical nanoparticles grown in a silicate glass at different temperatures with respect to the glass transition temperature were studied using high-resolution, low-frequency Raman scattering and optical absorption. The analysis of the spectra shows that the annealing of the doped glass at temperatures close to T-g leads to the formation of metallic copper nanoparticles with high crystallinity, whereas lower-temperature and higher-temperature annealings result in the formation of poorer nanoparticle assemblies in terms of size distribution and/or nanocrystallinity. It is also shown that in the case where the optical data do not unambiguously…
Raman, electron microscopy and electrical transport studies of x-ray amorphous Zn-Ir-O thin films deposited by reactive DC magnetron sputtering
2015
Zn-Ir-O thin films on glass and Ti substrates were deposited by reactive DC magnetron sputtering at room temperature. Structural and electrical properties were investigated as a function of iridium concentration in the films. Raman spectrum of Zn-Ir-O (61.5 at.% Ir) resembles the spectrum of rutile IrO2, without any distinct features of wurtzite ZnO structure. SEM images indicated that morphology of the films surface improves with the iridium content. EDX spectroscopy and cross-section SEM images revealed that the films growing process is homogeneous. Crystallites with approximately 2-5 nm size were discovered in the TEM images. Thermally activated conductivity related to the variable range…
Disorder-induced Raman scattering in rhenium trioxide (ReO3)
2007
Raman scattering in cubic metallic perovskite (ReO3) was studied at room temperature for well-crystallized monolith, polycrystalline powder and thin film samples. Defect-induced first-order Raman scattering was detected from the sub-surface region, given by the penetration depth of a 633 nm laser, and its origin was explained on the basis of a rigid-ion vibrational model for bulk ReO3. A quenching of the Raman intensity was observed in crystalline monolithic ReO3 upon increasing the temperature up to 250 °C and was related to crystal surface reconstruction/annealing.