X-Ray K-Absorption Edges of Three-Planar Nickel Compounds

Abstract

The low-energy structure of the x-ray K-absorption edge of nickel in nickel dimethylglyoxime, nickel phthalocyanine, and potassium nickel cyanide is re-examined for evidence of the second-order transition, the excitation of a 1s electron to a bound orbital, plus the simultaneous excitation of a plasmon. A perturbation calculation indicates that such a process may be observable. The absorption data are consistent with this interpretation if the electron transition is to a perturbed 3d orbital of the K-excited nickel atom or a molecular orbital which in the LCAO—MO approximation contains some d orbital wave function. The appearance of two strong absorption maxima (2 and 6.5 eV) in nickel dimethylglyoxime is explained by the formation of two distinct molecular species when nickel dimethylglyoxime is precipitated from a basic solution of dimethylglyoxime by a nickel salt.