An experimental study of the low-lying electronic states of WO2

The 364 nm negative ion photoelectron spectrum of WO2- is obtained. The spe ctrum reveals that four different electronic states are accessed in the neu tral molecule following electron detachment. From the rich vibrational stru cture the vibrational frequencies of the bending and/or symmetric stretchin g vibrations are measured. The electron affinity is determined to be 1.998( 10) - 0.040k eV, where k = 0, 1, or 2. Theoretical calculations have been c arried out to determine the geometries, energies, and frequencies of the an ion and neutral molecules. These are utilized to generate a simulation of t he experimental spectrum. The excellent agreement between the spectrum and the simulation indicates that the changes in geometries upon detachment are well predicted by the theoretical method employed, at least for the two lo west electronic states. In addition, polarization studies enable us to dete rmine the asymmetry parameters for each state and thus confirm the assignme nts of the electronic states.