Perturbations in the 3sσg 1,3Πg Rydberg states of O2: Bound–bound interactions with the second 1Πg and 1Δg valence states

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Existing experimental (2+1) REMPI spectra for transitions into rotationally resolved levels of the 3sσg d 1Πg and 3sσg C 3Πg Rydberg states of O2 have been rotationally analyzed, resulting in the first characterization of rotational perturbations in d(v=1–3) and C(v=2). In addition, the results of this analysis have been interpreted with the aid of a coupled-channel Schrödinger-equation (CSE) model of the interacting electronic states. The identification and characterization of perturbations in the d and C states have allowed the nature of the interactions between the 3sσg 1,3Πg Rydberg states and the II 1Πg valence state to be clarified and a realistic empirical potential-energy curve for the II 1Πg state to be determined. While it is found that first- and second-order interactions with the II 1Πg valence state are responsible for the strongest perturbations observed in d(v=1–3) and C(v=2), additional weak perturbations found in d(v=2 and 3) are shown to result from a second-order interaction with the II 1Δg valence state. These weak perturbations, including an extra level observed for d(v=3, J=17), appear to be the first experimental evidence for the II 1Δg state, long predicted theoretically. Finally, detailed comparisons between experimental spectra and d 1Πg←←a 1Δg(1,0), (2,0) and (3,0) (2+1) REMPI spectra calculated using the CSE model are presented which support and illustrate these conclusions. © 1999 American Institute of Physics.

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