The (X (2)Pi(g)) ns sigma(g) (1,3)Pi(g) Rydberg states of O-2: Spectra, structures, and interactions

The results of a critical reexamination of previous experimental observatio ns of the (X (2)Pi(g)) ns sigma(g) (1,3)Pi(g) Rydberg states of O-2 are emp loyed to optimize a coupled-channel Schrodinger-equation (CSE) model descri bing rovibronic interactions among a number of (1,3)Pi(g) Rydberg and valen ce states. The results of calculations using this CSE model are compared wi th the experimental energy-level and predissociation linewidth data base. A s a result of the optimization process, relevant potential-energy curves an d Rydberg-valence, Rydberg-Rydberg, and valence-valence interactions are ch aracterized for (1,3)Pi(g) states in the similar to 6.5-9.5 eV region above the ground state of O-2. The precision of these characterizations and the interpretation of the experimental observations are found to be limited by the quality of the existing data, which exhibit a number of inconsistencies that cannot be reconciled without new, well-characterized experimental stu dies. In spite of these difficulties, the present CSE model, as currently p arametrized, represents a significant improvement over previous work, enabl ing identification of a number of previously unassigned spectral features a ssociated with perturbation of the 3s sigma(g) d (1)Pi(g) state by the para llel to (1)Pi(g) valence state and an anomalous J sensitivity in predissoci ation branching ratios for the d(v=1) level. In addition, the electronic st ructure and predissociation of the ns sigma(g) states for n greater than or equal to 4 are found to be strongly influenced by ns sigma(g)-(n-1)d sigma (g) Rydberg-Rydberg interactions. (C) 1999 American Institute of Physics. [ S0021-9606(99)00925-3].