On the role of rotational couplings in inelastic Ne*-Ne and Ar*-Ar collisions at thermal energies

The relatively large probability of the fine-structure transitions 3Psub(0-1), 3Psub(0-2) which are observed in Ne*-Ne collisions at thermal energies (E >approximately 80 meV) cannot be accounted for by the spin-orbit (SO) interaction. The Ar2* system is in some ways similar to Ne2*, apart from a larger SO interaction. The probability of the 3Psub(0→2) transition induced by the SO interaction is calculated for the Ar*-Ar collision at 326 meV and the effect of the rotational coupling (L+-) between Λ states 3Σ+sub(g) and 3PIsub(g), which are degenerate at infinite R, is examined in the framework of a simplified two-state (0-sub(g), 1sub(g)) model. (author)