Resonant electronic excitation in e⁻-O collisions

The excitation to the higher lying levels of the (2p 4 ) configuration of oxygen in the course of an e - -O collision is theoretically studied. The authors show that this excitation can be understood and represented as a resonant process involving the O - bound state as a collision intermediate. This resonant excitation process is studied within the effective range approximation that the authors previously developed on the e - -O 2 collisional system. Excitation cross sections for the 1 D and 1 S states are compared with previous experimental and theoretical results. Analysis of the high energy behaviour of the effective range results yields a simple means for a priori evaluating the importance of the resonant excitation process.