Moment analysis in depolarized light scattering: Determination of a single-parameter empirical pair polarizability anisotropy for Ne, Ar, Kr, Xe, and CH4

The two-body collision-induced light scattering spectra of pure SF 6 and CF4 and of their mixtures with inert gases have been measured at 295 K. The data were compared with calculations of the spectral profiles. These comparisons enabled: (i) the testing of a scaling law for the pair polarizability anisotropy responsible for the purely translational scattering; (ii) the determination of refined values for the magnitudes of the dipole-octopole polarizability ((10-7 + 2) x 10 -s~ m 5) of SF 6 and of the dipole-quadrupole ((2.5 + 0.3) x 10-4~ 4) and dipole--octopole ((2.5 + 0.3) x 10-S~ 5) polarizabilities of CF4; and (iii) the assessment of the suitability of available intermolecular potentials for describing the interaction leading to the scattering, particularly for SF6-SF 6 , SF6-Kr and CF4-Ar.

Section: Review Of the Theorymentioning

confidence: 99%

“…In the molecular frame, for a pair of identical isotropic molecules, the total pair polarizability anisotropy contributing to the purely translational scattering has been modelled as [7] fl(X)=I6Ot2oX-3+(6~ao+~C6~x-6--Bexp(--X/Xo)l, 3Ctoj (1) with X = R/Rmi,,. Here ~o is the polarizability of a single molecule, ?…”

Section: Review Of the Theorymentioning

confidence: 99%

Perturber dependence of the collision-induced light scattering by SF₆and CF₄

El‐Sheikh

Tabisz

1989

“…The DID model leads to a spectral shape significantly wider than the experimental data, and the SCF model of Dacre leads to a spectral shape decreasing too fast with frequency shifts. Unlike what was found for argon [19, 26, [40], and continuous line: MTZ model [41]. The Aziz intermolecular potential [28] was used for every calculation.…”

Section: Resultsmentioning

confidence: 99%

“…In these calculations three different polarizability models were tested for the anisotropy: The asymptotic dipole induced dipole (DID) model [2, 391, the selfconsistent field calculation (SCF) of Dacre [40], and the empirical model of Meinander et al (MTZ) [41]:…”

Section: Cir-pa ( T ) = -C C ( P F X ' " ' ( M a T )mentioning

confidence: 99%

Three-body interaction-induced light scattering in krypton gas: a computer simulation of the spectral line shapes

Teboul

1999

The two-, three-and four-body effective collision induced scattering spectral line shapes are calculated for dense gaseous krypton using the pairwise additivity (PA) approximation and different polarizability models. These spectra and several interaction induced spectra calculated at various densities are compared with the experimental measurements of Barocchi et al. 11988, Europhys. Lett., 5, 6071. The potential effect on the spectrum is found to be weak. The results obtained with the Meinander e f al. [1986, J. chem. Phys., 84, 30051 empirical polarizability model and molecular dynamics fit well the experimental two-and three-body spectral shapes. The irreducible contribution to the spectral shape is evaluated using the dipole induced dipole irreducible polarizability [Buckingham, A. D., and Hands, I. D., 1991. Chem. Phys.Lett., 185, 5441. This contribution is found to be relatively weak for the anisotropic spectra in the frequency and density range studied, explaining the good agreement between the pairwise approximation calculations and the experimental data. The spectra radiated by the quasimolecules Krz, Kr3, and Kr4 (the total spectrum within the PA approximation) are also simulated.

“…Collision-induced light scattering (CILS) has been widely used in the past to study intermolecular properties, especially the invariant of the interactioninduced polarizability tensor of collisional pairs of atoms or molecules [1][2][3][4]. Accurate Raman spectra of the rare-gases could be recorded at low enough densities so that the spectra are due to binary interactions, virtually unaffected by many-body interactions.…”

Section: Introductionmentioning

confidence: 99%

Thermophysical properties and collision-induced light scattering as a probe for gaseous helium interatomic potentials

El-Kader

2012

Isotropic and anisotropic collision-induced light scattering spectra of helium gas at room temperature 294.5 K and at 99.6 K with the second pressure virial coefficients, second acoustic virial coefficients, viscosity and thermal conductivity have been used for deriving the empirical models of the pair-polarizability trace and anisotropy and the interaction potential. Theoretical zeroth and second moments of the binary spectra using various models for the pair-polarizabilities and interatomic potential are compared with the experimental values performed by Le Duff's group. In addition, third pressure virial coefficients, isotopic thermal factors, self diffusion coefficients, second virial dielectric constants and second Kerr coefficients calculated for these models are compared with experimental ones. The results show that these models are the most accurate models reported to date for this system.