Hyper Rayleigh collisional light scattering. Theoretical versus ab initio hyperpolarizability models.

Abstract

Collision-Induced hyper-Rayleigh light scattering (CIHRS) on super-molecular compounds composed of lighter noble gas atoms (He, Ne and Ar) and linear hydrogen molecules has been recently discussed within theoretical as well as numerical comparative spectral studies. The aim of the present report is to analyze updated results in this field of inter est generalized over the case of two heavier units of H2Kr and H2Xe. The roto-translational collisional profiles are obtained by means of quantum mechanical and semi-classical calculations. Tensorial symmetry adapted components of the first hyperpolarizability, Δβ -responsible for occurrence of the CIHRS processes -are applied on the grounds of previously calculated Cartesian quantities, found by means of the quantum chemistry (ab initio) methods. The spectral lines evaluated are partially treated as a benchmarking device to estimate the importance of the long-distance Δβ(R) dependence determined on the basis of the theoretical multipole-induced-multipole analytical model. Moreover, the magnitude of the CIHRS effect is discussed in regard to the experimental feasibility of CIHRS detection.

Morphology of collisional nonlinear spectra in H2-Kr and H2-Xe mixtures

“…The lines represent functional dependence of the collisional hyperpolarizability on the intermolecular distance between H 2 and a noble gas scatterer are evaluated by applying the Marquadt-Levenberg fitting algorithm 59 (a modelling formula together with fitting parameters are available from the corresponding author upon request). The fitted functions are determined within a relatively wide range of separations ranging from R = 4 to 14 a 0 that, according to earlier assessments, 60 provides a satisfactory range for calculating reliable spectral shapes.…”

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

“…Besides, a series of articles devoted to the so-called hyper-Rayleigh collisional scattering have appeared in which a comparative study on the evolution of collisional properties (hyperpolarizabilities in this case) within the whole set of the H 2 -Rg compounds is discussed. [41][42][43][44][45][46][47] The ideas formulated in the previous paragraphs find their practical realization in this work. Namely, Sec.…”