Avon P. Jayaweera, Bethmini Senevirathne, Samantha Weerasinghe, Naoki Watanabe, Gunnar Nyman, François Dulieu and W. M. C. Sameera*,
{"title":"关于冰中 CO2 + OH 阴离子反应的机理和量子隧穿:计算研究","authors":"Avon P. Jayaweera, Bethmini Senevirathne, Samantha Weerasinghe, Naoki Watanabe, Gunnar Nyman, François Dulieu and W. M. C. Sameera*, ","doi":"10.1021/acsearthspacechem.4c00073","DOIUrl":null,"url":null,"abstract":"<p >The mechanism of the reaction between CO<sub>2</sub> and OH<sup>–</sup> (anion) in ice cluster models was determined using density functional theory (DFT), employing the ωB97X-D functional and def2-TZVP basis sets for all atoms. A range of reaction barriers, 0.08–0.43 eV, were found, and the lowest energy path has a barrier of 0.08 eV, giving rise to the bicarbonate ion (HCO<sub>3</sub><sup>–</sup>). Computed rate constants, accounting for quantum tunneling by employing the Eckart potential, suggest that the CO<sub>2</sub> + OH<sup>–</sup> → HCO<sub>3</sub><sup>–</sup> reaction can operate in ice at low temperatures (e.g., 10 K). In contrast, relatively high reaction barriers (0.52–0.74 eV) were found for the CO<sub>2</sub> + OH<sup>•</sup> (radical) → HCO<sub>3</sub><sup>•</sup> (radical) reaction, and the computed rate constants at low temperatures (e.g., 10 K) are extremely small. Based on the computed data, we argue that OH<sup>–</sup> can react with CO<sub>2</sub> trapped in interstellar ice at 10 K, and the product of the reaction, HCO<sub>3</sub><sup>–</sup>, is stable in ice. On the other hand, the OH radical does not react with CO<sub>2</sub> in ice. Therefore, we propose that OH anions in interstellar ice play a role in the formation of precursors of complex organic molecules (COMs) in the interstellar medium. The present findings will open a new dimension to explore the chemical evolution in the interstellar medium through the chemistry of anions in interstellar ices.</p>","PeriodicalId":15,"journal":{"name":"ACS Earth and Space Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"On the Mechanism and Quantum Tunneling of the CO2 + OH Anion Reaction in Ice: A Computational Study\",\"authors\":\"Avon P. Jayaweera, Bethmini Senevirathne, Samantha Weerasinghe, Naoki Watanabe, Gunnar Nyman, François Dulieu and W. M. C. 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引用次数: 0
摘要
利用密度泛函理论(DFT)确定了冰簇模型中二氧化碳和OH-(阴离子)的反应机理,所有原子均采用ωB97X-D函数和def2-TZVP基础集。研究发现了 0.08-0.43 eV 的反应势垒范围,最低能量路径的势垒为 0.08 eV,产生碳酸氢根离子 (HCO3-)。利用埃卡特电势计算量子隧穿的速率常数表明,CO2 + OH- → HCO3- 反应可在低温(如 10 K)下在冰中进行。相反,我们发现 CO2 + OH- (自由基) → HCO3-(自由基)反应的反应势垒相对较高(0.52-0.74 eV),而且在低温(如 10 K)下计算出的速率常数极小。根据计算得出的数据,我们认为在 10 K 的温度下,OH- 可以与星际冰中的 CO2 发生反应,而反应产物 HCO3- 在冰中是稳定的。另一方面,OH 自由基不会与冰中的 CO2 发生反应。因此,我们认为星际冰中的 OH 阴离子在星际介质中复杂有机分子(COMs)前体的形成过程中发挥了作用。这些发现将为通过星际冰中阴离子的化学性质来探索星际介质的化学演化打开一个新的局面。
On the Mechanism and Quantum Tunneling of the CO2 + OH Anion Reaction in Ice: A Computational Study
The mechanism of the reaction between CO2 and OH– (anion) in ice cluster models was determined using density functional theory (DFT), employing the ωB97X-D functional and def2-TZVP basis sets for all atoms. A range of reaction barriers, 0.08–0.43 eV, were found, and the lowest energy path has a barrier of 0.08 eV, giving rise to the bicarbonate ion (HCO3–). Computed rate constants, accounting for quantum tunneling by employing the Eckart potential, suggest that the CO2 + OH– → HCO3– reaction can operate in ice at low temperatures (e.g., 10 K). In contrast, relatively high reaction barriers (0.52–0.74 eV) were found for the CO2 + OH• (radical) → HCO3• (radical) reaction, and the computed rate constants at low temperatures (e.g., 10 K) are extremely small. Based on the computed data, we argue that OH– can react with CO2 trapped in interstellar ice at 10 K, and the product of the reaction, HCO3–, is stable in ice. On the other hand, the OH radical does not react with CO2 in ice. Therefore, we propose that OH anions in interstellar ice play a role in the formation of precursors of complex organic molecules (COMs) in the interstellar medium. The present findings will open a new dimension to explore the chemical evolution in the interstellar medium through the chemistry of anions in interstellar ices.
期刊介绍:
The scope of ACS Earth and Space Chemistry includes the application of analytical, experimental and theoretical chemistry to investigate research questions relevant to the Earth and Space. The journal encompasses the highly interdisciplinary nature of research in this area, while emphasizing chemistry and chemical research tools as the unifying theme. The journal publishes broadly in the domains of high- and low-temperature geochemistry, atmospheric chemistry, marine chemistry, planetary chemistry, astrochemistry, and analytical geochemistry. ACS Earth and Space Chemistry publishes Articles, Letters, Reviews, and Features to provide flexible formats to readily communicate all aspects of research in these fields.