Excitation of semi-forbidden 2s22p23P-2s2p35S0and 2s2p2P0-2s2p24P lines observed in quasars

Collisional excitation by free electrons of transitions in various ions of the type 2s 2 2p q -2s2p q+1 , determines the strength of many semi-forbidden lines observed in quasars. Collision strengths for the transitions N + and O 2+ 2s 2 2p 2 3 P-2s2p 3 5 S 0 , and N 2+ 2s 2 2p 2 P 0 -2s2p 2 4 P are calculated from solutions of coupled integro-differential equations. In all cases allowance is made for configuration interaction between 2s 2 2p q and 2p q+2 , and all 2s2p q+1 channels are included.