MOLECULAR ORBITAL INTERPRETATION OF X-RAY ABSORPTION EDGES

The x-ray K absorption edges of transition metal ions in a number of covalent octahedral and tetrahedral complexes have been measured with a high-resolution double-crystal spectrometer. An analysis of the fine structure within about 20 eV of the edge in terms of molecular orbital theory has been attempted. For octahedral complexes a regular dependence of some features of the edge structures on the type of isomer and other perturbing effects of the ligands has been fairly well established. A correspondence of certain structural features to the ligand bond strengths and thus to the spectrochemical series has been predicted on the basis of MO theory and has been checked experimentally. For the chromates, manganates, and the [CrO3Cl -]- radical, reasonably satisfactory agreement of the experimental results with MO theoretical predictions has been obtained.