SELECTIVE-POPULATION OF SPIN-ORBIT LEVELS IN THE AUTOIONIZATION OF O(2)

Autoionization processes in O2 have been studied by measuring photoele ctrons in the photon energy region between the O2+ X2PI(g) and a 4PI(u ) ionic states (12.4-15 eV). The present experimental results provide comprehensive information about autoionization dynamics since the deca y routes from the spin-orbit components of the neutral autoionizing st ates to the two spin-orbit components of the ground ionic state are re solved. The intensity ratio of the O2+ X2PI1/2 and 1PI3/2 components h as been determined and strong OMEGA --> OMEGA+ selectivity has been ob served. The observed selectivity is explained in terms of a model in w hich the orbital angular momentum along the internuclear axis of the p ositive ion core remains unchanged during the autoionization process. Using this model, Rydberg orbitals of the I, I' and I'' autoionizing s tates are reassigned as 4ssigma(g), 3ddelta(g) and 3dsigma(g), respect ively, and the spin-orbit constant of the J state is determined.