Search results for " vibration"
showing 10 items of 296 documents
Raman study of self-assembled InAs/InP quantum wire stacks with varying spacer thickness
2008
http://link.aip.org/link/?JAPIAU/104/033523/1
Communication: Evidence of structural phase transitions in silicalite-1 by infrared spectroscopy
2013
The adsorption of trichloroethylene, perchloroethylene, and p-xylene on a MFI (Mobile-FIve) zeolite is studied using in situ FTIR spectroscopy at 298 K. Spectra of self-supported zeolites in contact with increasing pressures of pure gas were recorded at equilibrium in the mid-infrared domain. Analysis of the evolution of the shape and location of vibrational bands of the zeolite as a function of the amount adsorbed allowed the observation of structural modifications of the adsorbent for the first time by infrared spectroscopy.
A two-component model for the 2260cm−1 infrared absorption band in electron irradiated amorphous SiO2
2011
Abstract We report an experimental study by infrared absorption (IR) measurements focused on the effects of electron irradiation in the dose range from 1.2 × 10 3 kGy to 5 × 10 6 kGy on the intrinsic band peaked at 2260 cm − 1 in amorphous silicon dioxide (a-SiO 2 ) materials. This IR band is particularly relevant as it is assigned to an overtone of the strong asymmetric stretching vibration of Si–O–Si bridges and consequently it is intimately related to the Si–O–Si bond angle distribution. In a recent work we have shown that structural modifications induced by irradiation take place through the nucleation of confined high-defective and densified regions statistically dispersed into the w…
Infrared and Raman spectroscopy of WO3 and CdWO4
2001
Abstract Infrared reflection and Raman spectroscopy have been applied to study the vibrational modes of tungsten trioxide (WO 3 ) and cadmium tungstate (CdWO 4 ). Kramers–Kronig relations are employed to yield the refractive index as well as TO and LO functions of these materials at frequencies from 50 to 1200 cm −1 . The symmetry of the vibrations of CdWO 4 is reported.
Stability of FeVO4-II under Pressure: A First-Principles Study
2022
In this work, we report first-principles calculations to study FeVO4 in the CrVO4 -type (phase II) structure under pressure. Total-energy calculations were performed in order to analyze the structural parameters, the electronic, elastic, mechanical, and vibrational properties of FeVO4 -II up to 9.6 GPa for the first time. We found a good agreement in the structural parameters with the experimental results available in the literature. The electronic structure analysis was complemented with results obtained from the Laplacian of the charge density at the bond critical points within the Quantum Theory of Atoms in Molecules methodology. Our findings from the elastic, mechanic, and vibrational p…
The effects of whole-body vibration training on knee function and physical performance of middle-aged and elderly woman with knee osteoarthritis and …
2014
Effects of whole-body vibration exercise on muscular strength and power, functional mobility and self-reported knee function in middle-aged and older…
2013
Abstract Background Whole-body vibration training using vertical-vibration machines is called “acceleration training” (AT). The purpose of this study was to elucidate the effect of AT on lower-limb muscular strength and power, functional mobility and self-reported knee function in middle-aged and older Japanese women with knee pain. Methods Thirty-eight middle-aged and older Japanese women (aged 50–73 years) with knee pain were divided into two groups: (1) the AT group (n = 29) engaged in AT three times per week for eight weeks, and (2) the control group (C group, n = 9). The AT program consisted of flexibility training, strength training of mainly the quadriceps and surrounding muscles and…
Predicting the structure and vibrational frequencies of ethylene using harmonic and anharmonic approaches at the Kohn–Sham complete basis set limit
2016
In this work, regular convergence patterns of the structural, harmonic, and VPT2-calculated anharmonic vibrational parameters of ethylene towards the Kohn–Sham complete basis set (KS CBS) limit are demonstrated for the first time. The performance of the VPT2 scheme implemented using density functional theory (DFT-BLYP and DFT-B3LYP) in combination with two Pople basis sets (6-311++G** and 6-311++G(3df,2pd)), the polarization-consistent basis sets pc-n, aug-pc-n, and pcseg-n (n = 0, 1, 2, 3, 4), and the correlation-consistent basis sets cc-pVXZ and aug-cc-pVXZ (X = D, T, Q, 5, 6) was tested. The BLYP-calculated harmonic frequencies were found to be markedly closer than the B3LYP-calculated h…
Etude theorique de la dynamique du réseau de batio en phase quadratique
1999
Abstract The lattice dynamics of barium titanate BaTiO 3 is discussed quantitatively in the framework of a shell model taking into account the electronic polarizabilities of the constituent ions and including Coulomb and short-range interactions. The results of calculations point out the important role of the anisotropic oxygen polarizability. There is a good agreement between calculated and experimental dispersion curves.
Raman spectroscopic study of some lead phosphate glasses with tungsten ions
2006
Abstract The structure of x WO 3 · (100 − x )[2P 2 O 5 · PbO] glass system with 0 ⩽ x ⩽ 50 mol% was investigated by Raman spectroscopy. The characteristic bands of these glasses due to the stretching and bending vibrations were identified and analyzed by the increasing of WO 3 content. This fact allowed us to identify the specific structural units which appear in these glasses and thus to point out the network modifier role of tungsten oxide for low concentrations and its former role at high concentrations.