Ab initio calculations of the ³∑_g⁺ and 3∑_u⁺ states of singly excited Ar₂

CI calculations were performed for the 3∑g+ and 3∑u+ excimer states of Ar2 using molecular orbitals determined by MCSCF calculations. The 3∑u+ state has a small barrier and shallow well, as expected from analogy with other rare gas dimers. The deeply bound 3∑u,+ potential curve has a well depth of 0.68 eV at an internuclear separation of 4.59 a0. Elastic scattering on these curves was calculated and compared with experimental data. The primary rainbow from the 3∑u+ state is found to be in excellent agreement with observation. Copyright © 1976 American Institute of Physics.