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

The 364 nm negative ion photoelectron spectrum of WO2- is obtained. The spectrum reveals that four different electronic states are accessed in the neutral molecule following electron detachment. From the rich vibrational structure the vibrational frequencies of the bending and/or symmetric stretching 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 carried out to determine the geometries, energies, and frequencies of the anion and neutral molecules. These are utilized to generate a simulation of the 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 lowest electronic states. In addition, polarization studies enable us to determine the asymmetry parameters for each state and thus confirm the assignments of the electronic states.