ELECTRON-AFFINITY OF O- AND DIABATIC CAO(G) INTEGER CHARGE POTENTIAL CURVES

A ligand field, integer-charge ionic model for the electronic structure of diatomic CaO(g)provides a basis for an empirical deperturbation of the lowest lying 1Σ+ electronic states to their diabatic doubly charged (Ca2+O2-) and singly charged ionic (Ca+O-) potentials. The deperturbed doubly charged and lowest singly charged potentials cross at rCa-O = 2.16 (1) Å at an energy 10400 (100) cm-1 above v = 0 of the experimentally observed X1Σ+ ground state. The interaction matrix elements between the three lowest interacting 1Σ+ states have been determined as functions of rCa-O. With use of a simple Rittner model for the diabatic curves, extrapolation to infinite internuclcar separation yields a value for the electron affinity of O- (i.e. O- + e- → O2-) of -4.53 (6) cV, in agreement with quantum-Chemical results, and a value of 35 160 (200) cm-1 for D0° of CaO, in excellentagreement with thcrmochcmical values. © 1990, American Chemical Society. All rights reserved.