Transient Radiation-Induced Berkelium(III) and Californium(III) Redox Chemistry in Aqueous Solution

Despite the significant impact of radiation-induced redox reactions on the accessibility and lifetimes of actinide oxidation states, fundamental knowledge of aqueous actinide metal ion radiation chemistry is limited, especially for the late actinides. A quantitative understanding of these intrinsic radiation-induced processes is essential for investigating the fundamental properties of these actinides. We present here a picosecond electron pulse reaction kinetics study into the radiation-induced redox chemistry of trivalent berkelium (Bk(III)) and californium (Cf(III)) ions in acidic aqueous solutions at ambient temperature. New and first-of-a-kind, second order rate coefficients are reported for the transient radical-induced reduction of Bk(III) and Cf(III) by the hydrated electron (e(aq)(-)) and hydrogen atom (H-center dot), demonstrating a significant reactivity (up to 1011 M-1 s(-1)) indicative of a preference of these metals to adopt divalent states. Additionally, we report the first-ever second order rate coefficients for the transient radical-induced oxidation of these elements by a reaction with hydroxyl ((OH)-O-center dot) and nitrate (NO3 center dot) radicals, which also exhibited fast reactivity (ca. 10(8) M-1 s(-1)). Transient Cf(II), Cf(IV), and Bk(IV) absorption spectra are also reported. Overall, the presented data highlight the existence of rich, complex, intrinsic late actinide radiation-induced redox chemistry that has the potential to influence the findings of other areas of actinide science.

Automated summary

This study investigates the radiation-induced redox chemistry of berkelium and californium ions in acidic aqueous solutions. It reveals that these ions prefer to adopt divalent states and exhibits fast reactivity in reduction by hydrated electron and hydrogen atom, as well as in oxidation by hydroxyl and nitrate radicals. The absorption spectra of transient Cf(II), Cf(IV), and Bk(IV) are also reported. Overall, this research highlights the complex and intrinsic late actinide radiation-induced redox chemistry.