The Use And Limits Of The CIS Technique For The Measurements Of Hyperpolarizabilities : the H2-Rg case

Date du colloque&nbsp;: 10/2010</p

Dielectric-sphere-couple model for noble-gas pair polarizability

A classical model of two interacting dielectric spheres (DS) in an electric field is proposed to calculate the trace and anisotropy of the polarizability tensor of a pair of isotropic molecules. The case of noble gases is treated. It is shown that the dielectric-sphere-couple anisotropy is quite close to the dipole-induced-dipole (DID) anisotropy, while the DS trace is significantly greater than the DID trace, even at long distances between the interacting spheres. These results are interpreted as being due to the non-negligible multipolar contributions to the trace. To examine the validity of the model, its predictions are compared with results of experiments (trace and anisotropy are responsible for many collision-induced optical phenomena or properties) and of self-consistent-field calculations

Hyper-Rayleigh spectral intensities of gaseous Kr–Xe mixture

Binary collision-induced hyper-Rayleigh s CIHR d spectra of Kr–Xe gaseous system are computed quantum mechanically and classically within the frequency range up to 380 cm−1. The intensities are expressed in absolute units. The details of the theory developed for the CIHR spectra are given and the properties of the profiles as well as the depolarization ratio frequency dependence are discussed. The contributions to the spectra related to the vector b10(r) and the septor b30(r) components of the hyperpolarizability tensor are evaluated

Moments of hyper-Rayleigh spectra of selected rare gas mixtures

In this work we have analyzed spectral moments characterizing properties of the collisionally hyper-Rayleigh scattered light. This is a supplementary study undertaken in order to complete the series of our previously published papers on the collisional hyper-Rayleigh scattering spectral profiles. In order to evaluate the moments we have extended the theory so that it could embrace the hyper polarizabilities of higher rank. Using the expressions developed on the grounds of the theoretical principles and applying appropriate computational methods with ab initio hyperpolarizability values as an input, we have obtained desirable moment values for three diatomic noble gas systems: HeNe, HeAr, and NeAr, at several temperature points. The semiclassical and the quantum treatments have been taken into account, and the moments were calculated both from the sum rule method as well as from the spectral profiles. The results were compared and discussed

Introduction à la thermodynamique

Cet ouvrage est une introduction à la thermodynamique physique, dite " classique " et à l\u27étude des machines thermiques. Il s\u27adresse principalement aux étudiants en Licence et Licence professionnelle de Sciences de la matière, aux élèves des écoles d\u27ingénieurs et aux candidats aux concours de l\u27enseignement. Des exercices corrigés viennent en appui de chaque chapitre abordé

Etudes de propriétés de la matière par diffusion de la lumière

The scattering of light, means of investigation of the properties of matter, is considered here through two areas of application, one related to the physics of condensed states, the other to molecular physics. The first chapter is a brief summary of the pHD: dynamics of phase transitions of the ammonium hydrogen hemihydrate oxalate crystal. The determination of the order parameter at atmospheric pressure, the identification and characterization of a high pressure incommensurate phase are the main results. The second chapter deals with various aspects of linear and nonlinear scattering by pairs of interacting molecules. Experimental aspect: presentation of the light scattering set up of POMA Laboratory, designed for detecting extremely low light output. Theoretical aspect: tensor modeling of dielectric spheres polarizability. Comparison of experience and theory: determination of the multipolar polarizabilities of the globular molecules CF4, SF6 and CH4 by comparing the isotropic and anisotropic CILS spectra near the Rayleigh line and near the vibration Raman line nu1, by using set-inversion and by comparing extrapolated values with the values ​​calculated ab initio. Feasibility study: determination of the hyper-Rayleigh spectrum induced in the case of SF6 centrosymmetric molecule and its intensity in relation to known hyper-Rayleigh spectrum of CCl4

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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