Collision-induced rotational Raman scattering by tetrahedral and octahedral molecules

Contributions of Multipolar Polarizabilities to the Isotropic and Anisotropic Light Scattering Induced by Molecular Interactions in Gaseous Sulfur Hexafluoride

The binary isotropic and anisotropic collision-induced light scattering spectra of the gaseous sulfur hexafluoride at room temperature are analyzed in terms of recent intermolecular potential and interaction-induced pair polarizability models, using quantum line-shapes computations. The spectra at relatively low frequencies are determined largely by the effect of bound and free transitions. At intermediate frequencies the spectra are sensitive to both the attractive part of the potential and the short-range part of the polarizability trace and anisotropy. The high frequency wings are discussed in terms of the collision-induced rotational Raman effect and estimates for the dipole–octopole polarizability E, is obtained and checked with recent ab initio theoretical value. Absolute zeroth moment of both spectra have been measured and compared with theoretical calculations using different models of the intermolecular potentials. Also, the temperature dependence of the pressure second virial coefficient, viscosity and thermal conductivity are also discussed for the proposed potentials. The results show that (M3SV) is the most accurate potential yet reported for this system.

MOLECULES IN OPTICAL, ELECTRIC, AND MAGNETIC FIELDS: A Personal Perspective

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▪ Abstract  Physical chemistry and theoretical chemistry have advanced over the past 50 years from being largely qualitative to having a mature status based firmly on the principles of quantum and statistical mechanics. My interest in the chemical elements and their compounds has prompted me to learn more about the nature of matter through the measurement and interpretation of optical, electric, and magnetic properties of molecules. In addition to holding intrinsic interest, such properties tell us about charge and current distributions and form the basis of electro-optics, magneto-optics, and nonlinear optics. They also help us understand the nature and strength of long-range intermolecular forces, the hydrogen bond, and molecular biology—topics that are apparently forever young.

A molecular theory of new differential light­-scattering effects in a fluid

A molecular theory is presented of new differential light-scattering effects in a fluid, whose existence has been qualitatively predicted by recent symmetry-based arguments. These new effects, both natural and field-induced, differ from the known circular intensity differentials in the use, first, of additional polarization states for the incident beam and for the analysis of the scattered light and, secondly, of different directions of any applied field. To explain all the new intensity differentials the present theory has had to extend existing ones by including the contributions to the scattered radiation of the electric octopole and magnetic quadrupole induced in a molecule. Many of the new differentials are too small to be measured currently and only those of magnitude comparable with existing effects are presented. Some of these are independent of the various known circular intensity differentials and include an effect which provides a means in principle for measuring the high-frequency magnetizability of an atom.