The radiolysis of water is ubiquitous in nature and plays a critical role in numerous biochemical and technological applications. Although the elementary reaction pathways for ionized water have been studied, the short-lived intermediate complex and structural dynamic response after the proton transfer reaction remain poorly understood. Using a liquid-phase ultrafast electron diffraction technique to measure the intermolecular oxygen···oxygen and oxygen···hydrogen bonds, we captured the short-lived radical-cation complex OH(H₃O⁺) that was formed within 140 femtoseconds through a direct oxygen···oxygen bond contraction and proton transfer, followed by the radical-cation pair dissociation and the subsequent structural relaxation of water within 250 femtoseconds. These measurements provide direct evidence of capturing this metastable radical-cation complex before separation, thereby improving our fundamental understanding of elementary reaction dynamics in ionized liquid water.

中文翻译：

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离子化液态水中短寿命羟基-水合氢对成像

水的辐射分解在自然界中无处不在，在众多生化和技术应用中发挥着关键作用。尽管已经研究了离子水的基本反应途径，但质子转移反应后的短寿命中间复合物和结构动态响应仍然知之甚少。利用液相超快电子衍射技术测量分子间氧···氧和氧···氢键，我们捕获了短寿命自由基-阳离子配合物OH(H ₃ O ⁺) 通过直接的氧···氧键收缩和质子转移在 140 飞秒内形成，然后在 250 飞秒内自由基-阳离子对解离和随后的水结构弛豫。这些测量提供了在分离前捕获这种亚稳态自由基阳离子复合物的直接证据，从而提高了我们对离子化液态水中基本反应动力学的基本理解。