Intermolecular polarizabilities in H2-rare-gas mixtures (H2–He, Ne, Ar, Kr, Xe): Insight from collisional isotropic spectral properties

Abstract

The report presents results of theoretical and numerical analysis of the electrical properties related to the isotropic part of the polarizability induced by interactions within compounds built up of a hydrogen H2 molecule and a set of noble gas atoms, Rg, ranging from the least massive helium up to the heaviest xenon perturber. The Cartesian components of the collisional polarizabilities of the H2-Rg systems are found by means of the quantum chemistry methods and their dependence on the intermolecular distance is determined. On the basis of these data, the spherical, symmetry adapted components of the trace polarizability are derived in order to provide data sets that are convenient for evaluating collisional spectral profiles of the isotropic polarized part of light scattered by the H2-Rg mixtures. Three independent methods of numerical computing of the spectral intensities are applied at room temperature (295 K). The properties of the roto-translational profiles obtained are discussed in order to determine the role played by contributions corresponding to each of the symmetry adapted parts of the trace polarizability. By spreading the analysis over the collection of the H2-Rg systems, evolution of the spectral properties with the growing masses of the supermolecular compounds can be observed.

Effects of anisotropic interaction-induced properties of hydrogen-rare gas compounds on rototranslational Raman scattering spectra: Comprehensive theoretical and numerical analysis

“…Basically, this scenario follows the steps applied in the earlier work 16 on the collisional isotropic light scattering, although adequately adapted and upgraded according to the specific physical nature of the present research (order of the tensorial properties) and taking into account the updated state of knowledge. Therefore, only the most essential or newly introduced details are announced below.…”

“…They have proved their usefulness in the earlier spectral calculations of the isotropic Rayleigh spectra on H 2 -Rg pairs. 16 It must be stressed, however, that whenever necessary, the spectral routines employed in the presented research are no doubt capable of incorporating the available state of the art potential energy surfaces if only they are expressed analytically in the well known form of the Legendre expansion 74…”

“…A detailed description of their properties and basic steps has been presented in a number of earlier reports (most recently in Ref. 16). For this reason, only the most crucial outline of their workings is presented hereafter, unless more elaborate specification of newly introduced elements seems to be necessary.…”

“…The conventions and notation used are identical to those explained in Ref. 16. The rotational contribution to the spectrum is derived in a standard way on the grounds of a well-known quantum mechanics procedure 10,81 yielding a spectral stick distribution of a discrete set of intensities that are next "enveloped" with the translational profiles, (QI,cl) g (2) λ L (ω), rendering the overall rototranslational line shape (for details see Ref.…”

“…The former category of phenomena is represented, for instance, by investigations into nonlinear CI scattering processes on the complete (except Rn) collection of H 2 -Rg compounds undertaken in a series of works by the authors of this paper. [10][11][12][13] The isotropic CI Raman light scattering, which, after a rather lengthy silence has received fresh attention only recently, [14][15][16][17][18][19] is a typical example of latter works. The current work may be treated as a continuation and development of some of the earlier projects presented in Refs.…”