Analysis of the A 2Πu-X 2Π g band system of O2+ shows that the spin-orbit coupling constants for both states vary markedly with vibrational quantum number; in addition, the sign of that for certain levels of the A 2Πu state is uncertain. This is adequately explained for the X 2Πg state on the basis of a variation of the electronic expectation value of the spin-orbit coupling with internuclear distance, the major variation coming not from the variation of the contributions of the four configurations in the wavefunction, but from variation with internuclear distance of the form of the 1πg orbital. For the A 2Πu state, it was not possible to obtain quantitative agreement, since the coupling constant in this case is a small number, the difference between two large quantities. However, it seems clear that in this case the variation was mainly due to variation in the contributions of the various configurations. Copyright © 1975 American Institute of Physics.
