通过"激进 + 冰"机制,在星际脏冰罩上对甲基甲酸盐和甘甲形成的原子模型
Jessica Perrero1,2,3, Stefano Pantaleone2, Piero Ugliengo2
1Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Via dell'Elce di Sotto 8, I-06123, Perugia, Italy.
ChemPlusChem
|September 19, 2025
概括
甲基甲酸盐 (MF) 和甘醇 (GA) 是关键的星际分子. 这项研究模拟了它们在冰面上的形成,发现MF的较弱的结合能量解释了其较高的观测丰度,尽管能量有利于GA.
科学领域:
- 天体化学是天体化学.
- 星际介质的化学介质
- 计算化学的计算化学
背景情况:
- 甲基甲酸盐 (MF) 和甘醇 (GA) 是星际介质 (ISM) 中发现的原始有机分子.
- 现有的星际冰化学模型难以协调观察到的MF和GA的丰度,特别是在不同的ISM区域.
- 提出了谷物表面反应途径,但普遍的机制有利于GA形成而不是MF,从而与观测数据产生不匹配.
研究的目的:
- 在星际污冰上对MF和GA的合成反应进行原子模型.
- 调查涉及气相反应剂和冰冷CO的"激素+冰"机制.
- 确定控制MF和GA在ISM中的相对丰度的因素.
主要方法:
- 运用计算化学模拟不同H2O和CO百分比的表面上的MF和GA形成路径.
- 模拟了MF (OCH3 + CO_ice) 和GA (CH2OH + CO_ice) 两种两步"激素 + 冰"机制.
- 计算了反应能量障碍和分子结合能量的星际冰相似物.
主要成果:
- 形成MF的初始反应步骤具有显著的能量屏障 (32-38kJ/mol),而GA的形成则具有较低的屏障 (17-20kJ/mol).
- 在这两种路径中的第二个反应步骤几乎没有障碍.
- 在星际冰上,MF表现出较弱的结合能 (16.8-46.1 kJ/mol) 与GA (28.4-90.2 kJ/mol) 相比.
结论:
- 能量因素有利于GA的形成,但MF的较高观察到的丰度更好地解释为脱吸现象,而不是反应障碍.
- 在星际颗粒上MF的较弱的结合能使其在ISM中更丰富.
- 这项研究为太空中关键有机分子的形成途径和丰富性驱动因素提供了更精细的理解.
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