近日，西安交通大学任雪光团队报道了二氧化碳的双电离产生分子氧：一种漫游机制。相关论文发表在2026年1月1日出版的《中国物理快报》杂志上。

非生物氧形成早于光合作用，曾维系早期化学演化进程，但其基本反应机制仍存在争议。

研究组揭示了双电离二氧化碳在电子撞击下生成分子氧的路径。通过碎片离子与电子符合动量成像技术，结合测量投射粒子能量损失与C⁺ + O₂⁺反应通道，明确解析了电离机制。进一步的势能面与轨迹计算阐明了该碎裂过程的动力学细节：其中键重排路径通过结构变形形成三角形中间体进行。

此外，研究组发现CO₂²⁺生成O₂⁺还存在一种漫游反应路径——受挫的碳氧键解离使氧原子未能获得足够逃逸能量，随后氧原子在平坦势能面的构型空间中游荡，最终形成C–O–O²⁺中间体，继而产生终产物C⁺ + O₂⁺。鉴于星际空间中存在大量自由电子，该研究揭示的过程具有重要科学意义，应被纳入大气演化模型。

附：英文原文

Title: Double Ionization to CO2 Produces Molecular Oxygen: A Roaming Mechanism

Author: Qibo Ma, Xintai Hao, Jiaqi Zhou, Xiaorui Xue, Qingrui Zeng, Peng Li, Lei Wang, Xueguang Ren

Issue&Volume: 2026-01-01

Abstract: Abiotic oxygen formation predates photosynthesis, sustaining early chemical evolution, yet its elementary mechanisms remain contested. Here, we show the production pathways for molecular oxygen from doubly ionized carbon dioxide upon electron-impact. Through fragment ions and electron coincidence momentum imaging, we unambiguously determine the ionization mechanism by measuring the projectile energy loss in association with the C+ + O2+ channel. Further potential energy and trajectory calculations enable us to elucidate the dynamical details of this fragmentation process, in which a bond rearrangement pathway is found to proceed via the structural deformation to a triangular intermediate. Moreover, we demonstrate a further roaming pathway for the formation of O2+ from CO22+, in which a frustrated C-O bond cleavage leaves the O atom without sufficient energy to escape. The O atom then wanders around varied configuration spaces of the flat potential energy regions and forms a C-O-O2+ intermediate prior to the final products C+ + O2+. Considering the large quantities of free electrons in interstellar space, the processes revealed here are expected to be significant and should be incorporated into atmospheric evolution models.

DOI: 10.1088/0256-307X/43/1/010301

Source: https://cpl.iphy.ac.cn/article/doi/10.1088/0256-307X/43/1/010301