Molecular Beam Scattering Experiments On Species Of Atmospheric Relevance: Potential Energy Surfaces For Clusters And Quantum Mechanical Prediction Of Spectral Features

Abstract

Accurate intermolecular potential energy surfaces for the major compo- nents of the atmosphere, leading to the characterization of the O2-O2, N2-N2 and N2-O2 dimers, have been obtained from the analysis of scattering experiments from our laboratory, also exploiting where avail- able second virial coefficient data. A harmonic expansion functional form describes the geometries of the dimers and accounts for the rel- ative contributions to the intermolecular interaction from components of different nature. For O2-O2, singlet, triplet and quintet surfaces are obtained accounting for the role of spin-spin coupling. The new sur- faces allow the full characterization of structure and internal dynamics of the clusters, whose bound states and eigenfunctions are obtained by exact quantum mechanics. Besides the information on the nature of the bond, these results can be of use in modelling the role of dimers in air and the calculated rotovibrational levels provide a guidance for the analysis of spectra, thus establishing the ground for atmospheric monitoring. The same approach is currently being extended to simple hydrocarbons and water molecules interacting with rare gas atoms or simple molecules.