Shepard Christopher, Kanai Yosuke
Department of Chemistry, University of North Carolina at Chapel Hill, NC, USA.
Phys Chem Chem Phys. 2022 Mar 2;24(9):5598-5603. doi: 10.1039/d1cp05313b.
Nonlinear dynamics of electronic excitation bridge physical and physicochemical stages of water radiolysis under proton irradiation, a multi-scale physicochemical process that is fundamental to a wide range of technological and medical applications of high-energy protons. We study the spatial and temporal changes to the excited holes generated in this ionization event using first-principles theory simulation. A significant majority of holes are formed in the immediate vicinity of the irradiating proton paths, and these holes decay rapidly, while secondary excitations are simultaneously induced in regions farther away. While the hole population remains constant, the observed spatially spreading hole distribution cannot be described as concentration-dependent diffusion current. Compared to the primary excitation induced by the irradiating protons, the secondary excitation farther away is somewhat less energetic. The first-principles theory simulation here provides a detailed description of how the primary excitation by proton radiation precedes the formation of cationic holes, which undergo ultrafast chemical processes in water radiolysis.
质子辐照下水辐射分解的电子激发桥接物理和物理化学阶段的非线性动力学，这是一个多尺度物理化学过程，对高能质子的广泛技术和医学应用至关重要。我们使用第一性原理理论模拟研究了此电离事件中产生的激发空穴的时空变化。绝大多数空穴在辐照质子路径的紧邻区域形成，这些空穴迅速衰减，同时在更远的区域诱导二次激发。虽然空穴数量保持不变，但观察到的空间扩展空穴分布不能描述为浓度依赖的扩散电流。与辐照质子诱导的初级激发相比，更远区域的二次激发能量稍低。这里的第一性原理理论模拟详细描述了质子辐射的初级激发如何先于阳离子空穴的形成，阳离子空穴在水辐射分解中经历超快化学过程。
