Electron-impact excitation of neon at intermediate energies

Large-scale R matrix with pseudostates calculations for electron collisions with neon atoms, using a recently developed parallel version of our B-spline R-matrix code, are reported. The calculations were carried out in the jK-coupling scheme. They are intended to provide converged (with respect to the number of coupled states) results for electron impact excitation of individual target states with dominant configurations 2p(5)3s, 2p(5)3p, and 2p(5)3d for incident electron energies from threshold to 300 eV. The close-coupling expansion includes 457 target states, with the lowest 87 states representing the bound spectrum and the remaining 370 the ionization continuum. The results reveal dramatic reductions of the predicted excitation cross sections at intermediate energies due to a strong influence of coupling to the target continuum and the higher-lying Rydberg states. Comparison with available experimental data for the excitation of the 2p(5)3s and 2p(5)3p states raises questions about the absolute normalization in the measurements. Considerable improvement over previous work is obtained in the agreement between experiment and theory for the angle-differential cross sections. In particular, a long-standing discrepancy regarding the angular dependence for excitation of the metastable 2p(5)3s levels is resolved.