Horne Gregory P, Rotermund Brian M, Grimes Travis S, Sperling Joseph M, Meeker David S, Zalupski Peter R, Beck Nicholas, Huffman Zachary K, Martinez Daniela Gomez, Beshay Andrew, Peterman Dean R, Layne Bobby H, Johnson Jason, Cook Andrew R, Albrecht-Schönzart Thomas E, Mezyk Stephen P
Center for Radiation Chemistry Research, Idaho National Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415, United States.
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
Inorg Chem. 2022 Jul 18;61(28):10822-10832. doi: 10.1021/acs.inorgchem.2c01106. Epub 2022 Jul 1.
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) and hydrogen atom (H), demonstrating a significant reactivity (up to 10 M s) 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) and nitrate (NO) radicals, which also exhibited fast reactivity (ca. 10 M s). 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.
尽管辐射诱导的氧化还原反应对锕系元素氧化态的可及性和寿命有重大影响，但关于锕系元素金属离子水溶液辐射化学的基础知识仍然有限，尤其是对于后锕系元素。定量理解这些内在的辐射诱导过程对于研究这些锕系元素的基本性质至关重要。我们在此展示了一项皮秒电子脉冲反应动力学研究，该研究针对室温下酸性水溶液中三价锫（Bk(III)）和锎（Cf(III)）离子的辐射诱导氧化还原化学。报告了新的、首创的二阶速率系数，用于描述水合电子（e）和氢原子（H）对Bk(III)和Cf(III)的瞬态自由基诱导还原反应，这表明其具有显著的反应活性（高达10 M⁻¹ s⁻¹），表明这些金属倾向于形成二价态。此外，我们还报告了这些元素与羟基（OH）和硝酸根（NO）自由基反应的瞬态自由基诱导氧化反应的首个二阶速率系数，其反应活性也很快（约10 M⁻¹ s⁻¹）。还报告了瞬态Cf(II)、Cf(IV)和Bk(IV)的吸收光谱。总体而言，所呈现的数据突出了丰富、复杂的后锕系元素内在辐射诱导氧化还原化学的存在，这有可能影响锕系元素科学其他领域的研究结果。
