Hund's state conservation rule predicts (1 × 6) [N (4S) + O(-)(2P)] plus 9 × 9 [(3P) N(-) + O(3P)] = 87 spin states for NO(-). The experimental Ea(NO) , 0.92(2)-0.16(2) eV are assigned to the (3 + 27) bonding states with anion bond orders, 0.80-1.15. The Ea(NO) 0.026(5)-0.14(2) eV are assigned to seven of the 27 nonbonding states with anion bond orders about one. The negative Ea(NO) for the 20 other nonbonding and 30 antibonding states are estimated. Ionic Morse potentials are calculated for 87 predicted states for NO(-) and the 54 bonding and antibonding states of superoxide.

Theoretical adiabatic electron affinities are often considered inaccurate because they are referenced to only a single value. Ground state electron affinities for all the main group elements and homonuclear diatomics were identified recently using the normalized binding energy of the hydrogen atom: [0.75420375(3)/2 = 0.37710187(1) eV]. Here we revisit experimental values and extend the identifications to diatomics in the G2-1 set. We assign new ground state electron affinities: (eV) Cl2, 3.2(2); Br2, 2.87(14); CH, 2.1(2); H2, 0.6 ; NH, 1.1, SiH, 1.90. Anion Morse potentials are calculated for H2 and N2 from positive electron affinities and for hyperfine superoxide states for the first time.