Previously unobserved vibrational structure is observed in the 3 g a ∏  and 1 g A ∏  states and is tentatively assigned. Further, a refined electron affinity of 3.0464 (7) eV for NiO2 is obtained as well as precise term energies for the a  and A  states of NiO2 of 0.3982 (7) and 0.7422 (10) eV, respectively. Numerous Franck-Condon forbidden transitions involving the doubly degenerate v2 bending mode are observed and ascribed to Herzberg-Teller coupling to an excited electronic state.