Identification of two 3Σu-←X3Σg- transitions of 16O2 near 88930 and 90780 cm-1.

New 16O2 photoabsorption cross-section measurements are presented for two bands near 88930 cm-1 and 90780 cm-1. We have assigned these bands as the (0,0) and (1,0) bands of the E′3Σu-←X3Σg- system, where the E′ state is a mixed state resulting from the coupling of 4pπu and 5pπu 3Σu- Rydberg states with the lowest 3Σu- valence state. In contrast to the E3Σu-←X3Σg- bands seen at lower energies, these bands show resolved rotational structure. Spectroscopic parameters for the upper levels have been derived using an effective Hamiltonian and cross-section band models. The observed levels are perturbed by spin-orbit interactions with nearby levels (v=1 and 2) of the 4pπu D′3Σu+ Rydberg state. In addition, transitions to the v=2 level of the perturber state have been observed near 90920 cm-1. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]