MODEL POTENTIAL CALCULATIONS OF THE NA-HE SYSTEM

The model potential method developed by Valiron et al. (1977, 1979) is applied to the calculation of the potential energies of the ground and excited states of the Na-He molecular system. The excellent agreement with the ab initio calculations and the stability of the results to variations in the model potential parameters establish the reliability of the method. Interesting features in the more highly excited states are observed. The calculated interaction energies are used to compute the profile of the fluorescence spectrum from optically thin Na vapour in the presence of He at moderate pressures. The theoretical results for the Na resonance line profile are compared with the experimental data of York et al.