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 Ne 4+ (the configurations 2s 2 2p 2 and 2s2p 3 ) explicitly in the close-coupling formalism, and three correlation configurations. The inclusion of the 2s2p 3 term leads to many resonances in the near-threshold region and therefore affects the collision strengths significantly. The techniques used to solve the (Ne 4+ +e - ) collision problem are also used to calculate energies for bound states of Ne 3+ . The calculated ionisation energies for Ne 3+ 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.