Dobrovolskii Denis, Denisov Sergey A, Sims Howard E, Mostafavi Mehran
Institut de Chimie Physique, Université Paris-Saclay, CNRS, Bâtiment 349, Orsay, 91405, France.
Central Laboratory, National Nuclear Laboratory, Sellafield, Seascale CA20 1PG, UK.
Phys Chem Chem Phys. 2024 Apr 17;26(15):11604-11610. doi: 10.1039/d4cp00157e.
Picosecond pulse radiolysis measurements were employed to assess the effectiveness of N in scavenging quasi-free electrons in aqueous solutions. The absorption spectra of hydrated electrons were recorded within a 100 ps timeframe across four distinct solutions with N concentrations of 0.5, 1, 2, and 5 M in water. The results revealed a concentration-dependent shift in the maximum absorption spectra of fully solvated electrons. Notably, at 5 M concentration, the maximum absorption occurred at 670 nm, in contrast to 715 nm observed for water. Intriguingly, the formation yield of hydrated electrons within the initial 5 ps electron pulse remained unaffected, showing that, even at a concentration of 5 M, N does not effectively scavenge quasi-free electrons. This is in disagreement with conclusions from stochastic models found in the literature. This observation has an important impact on understanding the mechanism of H formation in water radiolysis, which we discuss briefly here.
采用皮秒脉冲辐解测量来评估N在清除水溶液中准自由电子方面的有效性。在100皮秒时间范围内，记录了水中N浓度分别为0.5、1、2和5 M的四种不同溶液中水合电子的吸收光谱。结果显示，完全溶剂化电子的最大吸收光谱存在浓度依赖性位移。值得注意的是，在5 M浓度下，最大吸收发生在670 nm处，而水的最大吸收在715 nm处。有趣的是，在最初的5皮秒电子脉冲内，水合电子的形成产率不受影响，这表明即使在5 M的浓度下，N也不能有效地清除准自由电子。这与文献中随机模型得出的结论不一致。这一观察结果对理解水辐射分解中H形成的机制具有重要影响，我们在此简要讨论。
