The electronic structure of molecular oxygen and the rotational structure of the d(1)Pi(g) Rydberg state

As a major constituent of the terrestrial atmosphere, the O2 molecule plays an important role both in the attenuation of solar radiation and in the spectrum of the airglow and aurora. Photo absorption by O 2 to its complex excited state structure leads to predissociation and involves a host of other kinetic and radiative processes. Part of the work presented in the thesis constitutes a complete and critical review of what is presently known about the electronic structure of O2 in four broad areas: (1) the detailed electronic structure of the first six bound states of O2 (the 0 to ∼ 5 eV region), (2) the electronic structures around the B S -u3 state ( ∼ 5.5 to 7 eV above the X S -g 3 ), (3) the Rydberg and valence states of both u and g symmetry in the energy region between the dissociation limit of the B S -u3 state and the ionization limit of O2 ( ∼ 7 to ∼ 12 eV), and (4) a detailed characterization of the d Pg1 Rydberg state and its interaction with several valence states based on analysis of new, laser-based spectroscopic data.; Item (1) involves a reevaluation of the results of a number of recent spectroscopic studies and the calculation of the associated potential energy curves by use of the RKR method. Item (2) involves the compilation and presentation of semi-empirical and theoretical potential energy curves based on recent observations and calculations of states near the B S -u3 state. Item (3) involves a comprehensive review of the most recent experimental spectral observations of transitions to Rydberg states of u and g symmetry as well as collection and/or construction of semi-empirical and theoretical potential energy curves. Item (4) was motivated by problems encountered with experimental data during work on item (3) which prompted the present detailed rotational analysis of new high resolution spectra of the d Pg1 - a Dg1 and d Pg1 - b S +g1 transitions. Finally, the potential energy curves for all known electronic states of O2 (both experimental and theoretical) have been collected and summarized.