Fine-structure spectrum of O2–rare gas van der Waals molecules

Abstract

A simple analytically solvable model is presented for the rotation-vibration-spin states in O2–rare gas atom complexes, which predicts the form of the fine-structure spectrum. It is shown that this spectrum looks basically different from the pure O2 spectrum, due to the partial quenching of the O2 angular momentum by the anisotropic O2-rare gas interaction potential. The model contains two properties of the O2–X complex as parameters: the ground state average of the anisotropic potential 〈V2(R)〉0 and the end-over-end rotational constant 〈R−2〉0, where R is the O2–X distance. Adjusting these parameters yields quantitative agreement with the spectra that have recently been obtained from two different empirical potentials via accurate dynamical calculations. The model can be used for interpreting the experimental fine-structure spectrum of O2Ar which is currently being measured.