Chao Wen, Skog Robert, Frandsen Benjamin N, Jones Gregory H, Pham Kayla T, Okumura Mitchio, Sulbaek Andersen Mads P, Percival Carl J, Winiberg Frank A F
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.
Department of Chemistry, University of Helsinki, Helsinki, Finland.
Commun Chem. 2025 May 24;8(1):163. doi: 10.1038/s42004-025-01520-3.
In Venus's mesosphere, the observation/model discrepancy of molecular oxygen, O, abundance has been a long-standing puzzle. Chlorine atoms have been proposed as a catalyst to oxidize carbon monoxide through the formation of chloroformyl radicals (ClCO), removing O and ultimately generating CO. However, relevant kinetic studies of this catalytic cycle are scarce and highly uncertain. In this work, we report the spectrum of the ClCO radical between 210-520 nm using a multipass UV-Vis spectrometer coupled to a pulsed-laser photolysis flow reactor at 236-294 K temperature and 50-491 Torr pressure ranges. High-level ab initio calculations were performed to simulate the observed spectrum and to investigate the electronic structure. In addition, we observed the formation of molecular chlorine, Cl, and phosgene, ClCO, suggesting that both the terminal chlorine and the central carbon in the ClCO radical are reactive towards chlorine atoms. Most importantly, the reported spectrum will enable future measurements of essential kinetic parameters related to ClCO radicals, which are important in regulating the O abundance in Venus's mesosphere.
在金星的中间层，分子氧（O）丰度的观测值与模型值之间的差异一直是个长期存在的谜题。有人提出氯原子作为一种催化剂，通过形成氯甲酰基自由基（ClCO）来氧化碳 monoxide，从而消耗O并最终生成CO 。然而，关于这个催化循环的相关动力学研究很少且极不确定。在这项工作中，我们使用一台多程紫外 - 可见光谱仪与一个脉冲激光光解流动反应器联用，在236 - 294 K的温度范围和50 - 491 Torr的压力范围内，报告了ClCO自由基在210 - 520 nm之间的光谱。进行了高水平的从头算计算来模拟观测到的光谱并研究其电子结构。此外，我们观测到了分子氯（Cl）和光气（ClCO）的形成，这表明ClCO自由基中的末端氯和中心碳对氯原子都具有反应活性。最重要的是，所报告的光谱将使未来能够测量与ClCO自由基相关的关键动力学参数，这些参数对于调节金星中间层中的O丰度很重要。
