Detailed information for diatomics has been obtained from electronic spectroscopy measurements conducted at the level of rotational and fine structure resolution. However, extension of this approach to actinide-containing polyatomic molecules has proved to be a challenging step. The complications can be illustrated by considering previous studies of UO2 and UO2 . Theoretical calculations predicted that both the neutral molecule and the cation have linear centrosymmetric equilibrium structures. The ground state rotational constants were predicted to be near 0.16 cm -1 . This is large enough that vibronic bands should show rotational structure that would be readily resolved using a standard pulsed dye laser. The rotational structure is further simplified for the dominant OU O isotopologue where, due to the exchange symmetry, half of the parity doublets do not exist. Despite these considerations, the electronic spectra recorded to-date for OUO have exhibited disappointingly unresolved rotational band contours .