Modeling Rayleigh Scattering of Aerosol Particles

• Rayleigh scattering of naturally polarized lightwas studied for systems with atmospheric relevance represent-ing growing water clusters with adsorbed cis-pinonic acid. Thescattering intensity was computed from the static anddynamical polarizabilities of the clusters obtained by a recentlyderived methodology for classical polarizabilities, in whichApplequist equations for interacting polarizable dipoles areused together with point-dipoles and polarizabilities obtainedby quantum chemistry and decomposed into the atomicdomain by the so-called LoProp transformation generalized forfrequency dependence. The Applequist interaction was foundto yield scattering intensities 20% larger for a cluster consistingof 1000 water molecules, as compared to the method where allof the polarizabilities of molecules are added withoutinteractions. It was confirmed that scattering intensity depends quadratically on the number of water molecules in the cluster,and that it also increases quadratically with increase in the mass constituent of the foreign substance. The adsorption of the cis-pinonic acid increases the contribution to the scattering intensity stemming from the anisotropic polarizability, as compared tothe isotropic contribution. The ramifications of the method in predicting Rayleigh scattering and the earth’s albedo with respectto man-made and natural gas emission are briefly discussed.

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NATURVETENSKAP  -- Kemi -- Teoretisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Theoretical Chemistry (hsv//eng)

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