An unconventional method for measuring the Tc L₃-edge of technetium compounds

Tc L₃-edge XANES spectra have been collected on powder samples of SrTcO₃ (octahedral Tc⁴⁺) and NH₄TcO₄ (tetrahedral Tc⁷⁺) immobilized in an epoxy resin. Features in the Tc L₃-edge XANES spectra are compared with the pre-edge feature of the Tc K-edge as well as other 4d transition metal L₃-edges. Evidence of crystal field splitting is obvious in the Tc L₃-edge, which is sensitive to the coordination number and oxidation state of the Tc cation. The Tc L₃ absorption edge energy difference between SrTcO₃ (Tc⁴⁺) and NH₄TcO₄ (Tc⁷⁺) shows that the energy shift at the Tc L₃-edge is an effective tool for studying changes in the oxidation states of technetium compounds. The Tc L₃-edge spectra are compared with those obtained from Mo and Ru oxide standards with various oxidation states and coordination environments. Most importantly, fitting the Tc L₃-edge to component peaks can provide direct evidence of crystal field splitting that cannot be obtained from the Tc K-edge.