Solid-state formation of CO 2 via the H 2 CO + O reaction
Solid-state formation of CO 2 via the H 2 CO + O reaction
复制标题
通过 H 2 CO O 反应固态形成 CO 2
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
F. Dulieu
中科院分区：
文献类型：
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作者：
M. Minissale;M. Minissale;J. Loison;S. Baouche;S. Baouche;H. Chaabouni;H. Chaabouni;E. Congiu;E. Congiu;F. Dulieu;F. Dulieu
上下文尽管二氧化碳是星际冰中最丰富的物质之一，但在分子云的静止区域中二氧化碳冰的形成还没有完全了解。目标。通过甲醛分子在冷表面上在接近于在静止分子云中遇到的条件下氧化来研究CO2形成，以评估H2CO + O反应的效率和活化势垒。方法.甲醛冰暴露于O原子使用差分泵浦光束线。H2CO + O反应实验在两种不同的天体物理学感兴趣的表面（无定形水冰和氧化石墨）上进行，温度分别为10 K和55 K。通过红外光谱和质谱，通过使用RAIRS和程序升温脱附技术探测的产品。结果在本文中，我们表明，H2CO + O反应可以有效地在固相中形成二氧化碳。根据与实验数据拟合的模型，该反应的活化势垒估计为335 ± 55 K。结论.冷表面上的H2CO+O反应可以被添加到导致星际冰中二氧化碳的一系列途径中。在天体物理学上，静止分子云中的CO2丰度可能由宇宙颗粒上发生的三种反应来解释：CO + OH，CO + O和H2CO + O。
Context. The formation of carbon dioxide ice in quiescent regions of molecular clouds has not yet been fully understood, even though CO2 is one the most abundant species in interstellar ices. Aims. CO2 formation was studied via oxidation of formaldehyde molecules on cold surfaces under conditions close to those encountered in quiescent molecular clouds to evaluate the efficiency and the activation barrier of the H2CO + O reaction. Methods. Formaldehyde ices were exposed to O atoms using a differentially pumped beam line. The H2CO + O reaction experiments were carried out on two different surfaces of astrophysical interest (amorphous water ice and oxidised graphite) held at 10 or 55 K. The products were probed via infrared and mass spectroscopy by using RAIRS and temperature-programmed desorption techniques. Results. In this paper we show that the H2CO + O reaction can efficiently form carbon dioxide in the solid phase. The activation barrier for the reaction, based on a model fit to the experimental data, was estimated to be 335 ± 55 K. Conclusions. The H2CO+O reaction on cold surfaces can be added to the set of pathways that lead to carbon dioxide in the interstellar ices. Astrophysically, the abundance of CO2 in quiescent molecular clouds may potentially be explained by three reactions occurring on cosmic grains: CO + OH, CO + O, and H2CO + O.