Multipolar polarizabilities from interaction-induced Raman scattering

In this chapter the authors first give a general presentation of collision-induced scattering (CIS), also named interaction induced scattering. The different types of molecular interaction are mentioned, with a special emphasis on the multipolar polarizabilities contributions studied in the authors\u27 laboratories since the beginning of 1990s. The authors describe the setup and the experimental procedure used for the measurement of the scattering on an absolute scale. They also discuss the multipolar contributions to depolarized and isotropic CIS for specific molecular symmetries. Studies in the Rayleigh wings of isotropic molecules such as CF4 and SF6 and of linear molecules such as N2 and CO2 are presented. The authors also report on observations made in the wings of vibrational Raman bands of CF4 and SF6

Collection Angle Dependence of the Depolarization Ratio in Light Scattering Experiments

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High order polarizabilities from optical interaction-induced Spectroscopy

Multipolar polarizability contributions to the collision-induced light scattering spectra of optically isotropic molecules may be put in evidence in the Rayleigh wings and in the vicinities of the v1 Raman vibrational lines. Experiments on CH4 or CF4 (tetrahedral symmetry) and SF6 (octahedral symmetry) make possible evaluations of the multipolar polarizabilities provided that isotropic Rayleigh spectra and anisotropic Raman bands are obtained in some relatively large frequency ranges. These evaluations — in particular those based on set inversion analysis — constitute experimental references for quantum chemistry computations of the multipolar polarizabilities. In the case of CH4, CF4 and SF6, the agreement between experimental and ab initio values is quite good

Arterial inflammation in mice lacking the interleukin 1 receptor antagonist gene

Branch points and flexures in the high pressure arterial system have long been recognized as sites of unusually high turbulence and consequent stress in humans are foci for atherosclerotic lesions. We show that mice that are homozygous for a null mutation in the gene encoding an endogenous antiinflammatory cytokine, interleukin 1 receptor antagonist (IL-1ra), develop lethal arterial inflammation involving branch points and flexures of the aorta and its primary and secondary branches. We observe massive transmural infiltration of neutrophils, macrophages, and CD4(+) T cells. Animals appear to die from vessel wall collapse, stenosis, and organ infarction or from hemorrhage from ruptured aneurysms. Heterozygotes do not die from arteritis within a year of birth but do develop small lesions, which suggests that a reduced level of IL-1ra is insufficient to fully control inflammation in arteries. Our results demonstrate a surprisingly specific role for IL-1ra in the control of spontaneous inflammation in constitutively stressed artery walls, suggesting that expression of IL-1 is likely to have a significant role in signaling artery wall damage

Isotropic collision-induced scattering by CF4 in a Raman vibrational band

Light-scattering intensities and depolarization ratio data have been recorded at room temperature for gaseous tetrafluoromethane in the collision-induced band of the Raman vibrational line ν1=908 cm−1. For the first time, binary isotropic intensities of the ν1-Raman band are reported in absolute units for Stokes frequency shifts up to 110 cm−1. From comparison with theoretical semiclassical computations of the dipole-multipole spectrum contributions, evaluations of the first derivatives of the successive dipole-multipole polarizabilitytensors are provided. These results are coherent with those obtained from corresponding depolarized intensities. Moreover, the agreement with ab initio quantum-chemistry calculations of the CF4 multipolar polarizabilities is satisfactory

Collision-induced depolarized scattering by CF4 in a Raman vibrational band

Collision-induced scattering data have been recorded at room temperature for gaseous tetrafluoromethane in a frequency vicinity of the Raman vibrational line ν1=908 cm−1. For the first time, corresponding binary depolarized intensities have been measured in absolute units for frequency shifts up to 110 cm−1 from the band center. Comparison with theoretical semiclassical intensities computed from dipole-induced dipole and dipole-multipole light scattering mechanisms leads to an evaluation of the first derivative of the dipole-quadrupole polarizabilitytensor A′. This result is in good agreement with recent ab initio quantum-chemistry calculations of the CF4 multipolar polarizabilities

Multipolar polarizations of methane from isotropic and anisotropic collision-induced light scattering

The anisotropic and isotropic binary collision-induced spectra scattered by gaseous methane have been measured in absolute units up to 900 cm−1 from the Rayleigh line. Corresponding theoretical intensities taking into account multipolar polarizabilities have been calculated using a semiclassical procedure. From the analysis of, mainly, our isotropic scattering data, values of the dipole-quadrupole and dipole-octopole polarizabilities are deduced. They are found to be in good agreement with recent ab initio calculations

Isotropic collision-induced light scattering by gaseous

The binary isotropic collision-induced scattering spectra of the gaseous tetrafluoromethane has been measured in absolute units in the 50–150 cm-1 frequency range. Corresponding theoretical intensities taking into account multipolar polarizabilities have been calculated in a semiclassical way. From a comparison with experiment, the independent components of dipole-quadrupole and dipole-octupole polarizability tensors have been estimated. They have been compared with those previously deduced from depolarized spectrum and with recent theoretical ab initio calculations

Depolarized light scattering by CF4

Tetrafluoromethane gas depolarized scattering has been recorded at 294.5 K and 20.3 amagat in the frequency range 2-340 cm-1. Two-body depolarized scattered intensities have been measured in absolute units up to 150,cm-1. Theoretical intensities taking into account multipolar polarizabilities and several hyperpolarizability contributions have been calculated. From comparison with experiment, the independent components of the dipole-quadrupole and the dipole-octopole polarizability tensors have been estimated and checked with recent ab initio theoretical values