ELECTRONIC AND STRUCTURAL INVESTIGATIONS OF TECHNETIUM COMPOUNDS BY X-RAY-ABSORPTION SPECTROSCOPY

X-ray absorption near edge structure spectroscopy has been used to establish the chemical shifts of the technetium K edge in a range of compounds containing Tc in a variety of formal oxidation states. The edge positions span 19.9 eV from Tc metal to NH{sub 4}TcO{sub 4}. Strong correlation between chemical shift and formal oxidation state is observed. Extended X-ray absorption fine structure (EXAFS) spectroscopy of Tc{sub 2}(CO){sub 10} indicates that multiple scattering along the Tc-C-O vector is more important than direct Tc{center_dot}{center_dot}O scattering. TcO{sub 2} is shown by EXAFS to possess a distorted rutile structure with a closest Tc-Tc distance of 2.61 {Angstrom}. This is rationalized in terms of the Goodenough model for bonding in transition metal dioxides.