Behavior of Heptavalent Technetium in Sulfuric Acid under α‑Irradiation: Structural Determination of Technetium Sulfate Complexes by X‑ray Absorption Spectroscopy and First Principles Calculations
The
effect of α-radiolysis on the behavior of heptavalent technetium
has been investigated in 13 and 18 M H<sub>2</sub>SO<sub>4</sub>.
Irradiation experiments were performed using α-particles (<sup>4</sup>He<sup>2+</sup>, <i>E</i> = 68 MeV) generated by
the ARRONAX cyclotron. UV–visible and X-ray absorption fine
structure spectroscopic studies indicate that Tc(VII) is reduced to
Tc(V) under α-irradiation. Extended X-ray absorption fine structure
(EXAFS) spectroscopy measurements are consistent with the presence
of mononuclear technetium sulfate complexes. Experimental results
and density functional calculations show the formation of [TcO(HSO<sub>4</sub>)<sub>3</sub>(H<sub>2</sub>O)(OH)]<sup>−</sup> and/or
[TcO(HSO<sub>4</sub>)<sub>3</sub>(H<sub>2</sub>O)<sub>2</sub>] and
[Tc(HSO<sub>4</sub>)<sub>3</sub>(SO<sub>4</sub>)(H<sub>2</sub>O)]
and/or [Tc(HSO<sub>4</sub>)<sub>3</sub>(SO<sub>4</sub>)(OH)]<sup>−</sup> for 13 and 18 M H<sub>2</sub>SO<sub>4</sub>, respectively