On the interpretation of the photoelectron spectrum of NiCO -

Ab initio calculations have been carried out for the X ¹Σ ⁺, a ³Δ, b ³Σ ⁺ and c ³Π states of NiCO, using a large Gaussian basis set and an MCPF treatment of electron correlation. The calculated dissociation energies, D_e (kcal/mol), are X ¹Σ ⁺ (30.1), a ³Δ (11.5), b ³Σ (10.1) and c ³Π(4.3). An analysis of the relative cross sections for photodetachment indicates that the lower energy feature in the photoelectron spectrum of NiCO- results primarily from bound-free transitions to the c ³Π state, with some contribution from bound-bound transitions to both the b ³Σ ⁺ and c ³Π states.