Spectra of diatomic quasimolecules in intermediate Hund's coupling cases. The UV continua produced by Hg(6 3P2) + Ar collisions

•Collision-induced quasimolecular radiation was experimentally and theoretically investigated near the spin-forbidden line Hg(6 3P2- 6 1S0) in thermal collisions with argon atoms.•The adoption of the new intermediate coupling case for the calculations of energy terms and radiative features of quasimolecules led to a satisfactory description of spectral profiles produced in the experiments.•The spectrum of collision-induced Hg (3P2) + Ar radiation is a continuous band, the maximum of which is shifted to the short-wave region relative to the forbidden atomic line by a value of the order of kT. Collision-induced quasimolecular radiation was experimentally and theoretically investigated near the spin-forbidden line Hg(6 3P2- 6 1S0) in thermal collisions with argon atoms. The mechanism of removing for prohibition at a quantitative level can be understood in the framework of the intermediate, between “a” and “c” Hund's coupling cases. For the first time, the experimental spectrum of quasimolecular radiation was obtained for the system in question, and the comparison with theoretical results obtained earlier was carried out. The temperature dependence of the radiative decay rate of the mercury atom metastable state in collisions with argon atoms was also obtained.