The electronic spectrum of KCoF₃: Exchange effects

Abstract

An analysis of the absorption spectrum of KcoF₃ based on the weak field spin-orbit matrices has led to an assignment of all the doublet states of the d⁷ configuration using the parameters Dq = 780 cm^-l, F₂ = 1440cm^-l, F₄ = 104.5 cm^-l and the spin-orbit coupling constant 5 = 490 cm^-l. F₂ F₄, and < correspond to 91%, 94%, and 91% of their respective free ion values. The spectral absorption intensities of the spin forbidden transitions between 26000 and 40000 cm^-l are much too large to be accounted for by the conventional spin-orbit coupling mechanism and one involving exchange interactions between pairs of ions is indicated. Consistent with this mechanism 1s the appearance of nine absorption regions which correspond to the simultaneous electronic excitation of pairs of ions.