HIGH-RESOLUTION MANGANESE X-RAY-FLUORESCENCE SPECTROSCOPY - OXIDATION-STATE AND SPIN-STATE SENSITIVITY

K beta X-ray emission spectra have been recorded for Mn(II), Mn(III), and Mn(IV) compounds with a variety of ligands. The spectra have be interpreted and simulated as atomic multiplets perturbed by a crystal field. The X-ray fluorescence in this region, which results from 3p --> 1s transitions, is split between a strong K beta(1,3) region and a weaker K beta' satellite. For Mn(II) complexes, the K beta' region derives from final states with antiparallel net spins between the 3p(5) hole and the 3d(5) valence shell. The K beta(1,3) region is dominated by spin-parallel final states. For octahedral high-spin Mn(II), Mn(III), and Mn(IV) complexes, the K beta(1,3) peak position shifts to lower energy with increasing oxidation state. The K beta' feature is weaker and broader for the higher oxidation states, and it is almost unobservable for low-spin Mn(III). K beta fluorescence is a good probe of Mn spin state and oxidation state. Spin-selective X-ray absorption near-edge spectra, taken by monitoring specific K beta features, are illustrated. The potential for site-selective absorption spectroscopy, based on monitoring chemically sensitive K beta features, is discussed.