Configuration interaction (CI) calculations were performed for the X 2Σ A2Π, and B2Σ states of NaAr. The A2Π state is calculated to have a well depth of 492 cm -1 at an internuclear separation of 3.04 Å. Small wells of 55 and 32 cm-1 were found for the X2Σ and B 2Σ states located at 5.01 and 6.80 Å, respectively. The spectra for A2Π-X2Σ emission in the limits of zero and infinite Ar pressure were calculated and compared with the experiment of York, Scheps, and Gallagher and the predictions using the pseudopotential curves of Pascale and Vandeplanque. The potentials from this work give spectra in much better agreement with experiment than the pseudopotential predictions. Total and differential cross sections for fine-structure changing transitions Na(2P1/2)+Ar→Na(2P3/2)+Ar-17.2 cm-1 were calculated by a quantum mechanical technique. The total cross sections are in excellent agreement with experimental results. The excited state differential cross sections exhibit prominent rainbow structure centered at τR = EΘR = 5.5-6.0 eV deg. Copyright © 1977 American Institute of Physics.