OSCILLATOR-STRENGTHS FOR TRANSITIONS AMONG LOW-LYING QUARTET TERMS IN THE NITROGEN ISOELECTRONIC SEQUENCE

We have calculated energies and transition rates for the 2s(2)2p(3)4S-degrees ground state and a number of excited states in the isoelectronic sequence of atomic nitrogen using the multiconfiguration optimized potential model (MCOPM). The excited states include the 2s(2)2p(2)3s4P, 2s2p(4)4P, 2s(2)2p(2)3p4D-degrees, 2s(2)2p(2)3p4P-degrees, 2s(2)2p(2)3p4S-degrees, 2s(2)2p(2)3d4F, 2s(2)2p(2)3d4D 2s(2)2p(2)3d4P terms. The oscillator strengths for transitions among these terms have been calculated in both length and velocity gauge. Particular emphasis has been put on an accurate description near level crossings. Comparison with other theoretical and experimental results are made. However, the experimental data are rather sparse, and verification of many of the calculated trends against experiment is therefore not yet possible.