Valence and Rydberg States of FO: An ab Initio Search for Electronic Transitions

Abstract

An electronic absorption spectrum of FO has yet to be observed experimentally but as a guide for future spectroscopic studies of this radical, CASSCF/MRCI ab initio calculations have been performed to locate and identify the lowest energy valence and Rydberg states. No bound valence excited potentials were found save the a4Σ- state. The calculations provide estimates of the transition energies Te to the lowest Rydberg states and the wavelengths required for spectroscopic detection. Results for both the doublet and quartet states are presented, revealing the 3sσ, 3pπ, 3pσ, 3dδ, 4sσ, 3dπ, and 4dδ Rydberg orbitals. It is likely that the repulsive valence states 12Σ- and 12Δ predissociate the lowest Rydberg states of the same symmetry. Consequently, the 2Π Rydberg states, three of which are found here, are the most promising candidates for optical detection.