Coupling effects in electron-impact excitation of oxygenlike krypton

Abstract

Coupling effects among the channels for collisional excitation of 2s/sup 2/2p/sup 4/, 2s2p/sup 5/, and 2p/sup 6/ configurations of oxygen-like krypton have been investigated by comparing six-, five-, four-, three-, and two-state close-coupling (CC) cross sections for the electron collision energy range 26.2 Ryless than or equal toEless than or equal to500 Ry. We discovered the surprising result that the calculated three-state CC (3CC) cross sections for the transition from the ground state to the 2p/sup 6/ /sup 1/S/sup e/ and the two-state CC cross section to the other excited states are reduced (considerably (45%) for the former) when the 2s2p/sup 5/ /sup 3/P/sup o/ channel is added to the 5CC approximation. In addition, the 3CC cross section sigma(2p/sup 4/ /sup 3/P/sup e/--2p/sup 6/ /sup 1/S/sup e/) is diminished by a factor of 100 at 26.2 Ry by the addition of the 2s2p/sup 5/ /sup 3/P/sup o/ state. Approximations which omit the 2s2p/sup 5/ /sup 3/P/sup o/ state overestimate the cross sections.