ELECTRON-IMPACT EXCITATION OF NE4+ AND ENERGY-LEVELS OF NE3+

Calculations have been made of collision strengths for electron impact excitation transitions between the ground configuration terms of Ne 4+. The authors have used a configuration-interaction target consisting of the lowest nine terms in Ne4+ (the configurations 2s22p2 and 2s2p3) explicitly in the close-coupling formalism, and three correlation configurations. The inclusion of the 2s2p3 term leads to many resonances in the near-threshold region and therefore affects the collision strengths significantly. The techniques used to solve the (Ne4++e-) collision problem are also used to calculate energies for bound states of Ne3+. The calculated ionisation energies for Ne3+ ground configuration terms agree with experimental values to within about 0.3 per cent. For excited configurations calculated and experimental quantum defects generally agree to within 5 per cent. Calculated energies are given for a large number of levels for which experimental energies have not been determined.