Single and double addition of oxygen atoms to propyne on surfaces at low temperatures.
Single and double addition of oxygen atoms to propyne on surfaces at low temperatures.
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低温下氧原子在表面上单次和双次加成到丙炔上。
DOI：
10.1039/c3fd00130j
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发表时间：
2014
影响因子：
3.4
通讯作者：
Kimber HJ
中科院分区：
文献类型：
--
作者：
Kimber HJ
旨在模拟星际云中发生的低温表面化学的实验提供了氧原子和丙炔冰之间发生反应的明确证据。将反应物滴加到保持在 14 至 100 K 之间固定温度的表面上。滴加结束后，使用程序升温解吸 (TPD) 结合飞行时间质谱法来鉴定分子式为 C3H4O 和 C3H4O2 的两种反应产物。这些产物是通过将单个氧原子或两个氧原子添加到丙炔反应物中而产生的。使用一个简单的模型从表面温度为 30-100 K 的单加成 (C3H4O) 产物的测量产率中提取动力学数据。该模型表明，丙炔和单个氧原子 (160 ± 10 K) 之间的固态反应势垒比报道的气相反应小一个数量级。此外，通过建模确定了单次添加过程中丙炔解吸能和反应速率系数（作为温度的函数）的估计值。当表面温度从 50 K 降低到 30 K 时，单加成产物的产率下降，但当表面温度降至 30 K 以下时，单加成产物的产率再次上升。低表面温度下反应速率的增加表明了单加成产物的替代（可能是无障碍）途径，该途径仅在低表面温度下才重要。该动力学模型已得到进一步发展，以表征双加成反应，该反应似乎涉及向 C3H4O 添加第二个氧原子。该模型表明第二次添加是一个无障碍过程。我们从实验中提取的动力学参数表明，原子氧和丙炔之间的反应可能在天体物理时间尺度上的星际尘埃颗粒上发生。
Experiments designed to simulate the low temperature surface chemistry occurring in interstellar clouds provide clear evidence of a reaction between oxygen atoms and propyne ice. The reactants are dosed onto a surface held at a fixed temperature between 14 and 100 K. After the dosing period, temperature programmed desorption (TPD), coupled with time-of-flight mass spectrometry, are used to identify two reaction products with molecular formulae C3H4O and C3H4O2. These products result from the addition of a single oxygen atom, or two oxygen atoms, to a propyne reactant. A simple model has been used to extract kinetic data from the measured yield of the single-addition (C3H4O) product at surface temperatures from 30–100 K. This modelling reveals that the barrier of the solid-state reaction between propyne and a single oxygen atom (160 ± 10 K) is an order of magnitude less than that reported for the gas-phase reaction. In addition, estimates for the desorption energy of propyne and reaction rate coefficient, as a function of temperature, are determined for the single addition process from the modelling. The yield of the single addition product falls as the surface temperature decreases from 50 K to 30K, but rises again as the surface temperature falls below 30 K. This increase in the rate of reaction at low surface temperatures is indicative of an alternative, perhaps barrierless, pathway to the single addition product which is only important at low surface temperatures. The kinetic model has been further developed to characterize the double addition reaction, which appears to involve the addition of a second oxygen atom to C3H4O. This modelling indicates that this second addition is a barrierless process. The kinetic parameters we extract from our experiments indicate that the reaction between atomic oxygen and propyne could occur under on interstellar dust grains on an astrophysical time scale.
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DOI：
10.1086/429662
发表时间：
2005
期刊：
The Astrophysical Journal Letters
影响因子：
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作者：
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DOI：
--
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DOI：
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发表时间：
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DOI：
--
发表时间：
1983
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