岩石上的醇：在黑云条件下H3CCCH + OH混合物中固态形成
Alcohols on the rocks: solid-state formation in a H3CCCH + OH cocktail under dark cloud conditions
摘要：
最近的一些实验研究表明，固态复杂的有机分子（COM）可以形成的条件下，相关的CO冻结出阶段在密集的云。在这项工作中，我们表明，醇可以形成之前的CO冻结阶段（即，在富含H2O的冰相中）。这种联合实验和计算研究表明，异构体，正丙醇和异丙醇，（H3CCH 2CH 2 OH和H3CCHOHCH 3）和正-和异-丙烯醇（H3CCHCHOH和H3CCOHCH 2），可以在10 K的低温下由丙炔（H3CCCH）+ OH开始的自由基加成反应中形成，其中H3CCCH是已经在星际介质（ISM）中确定的稳定碳链的最简单的代表之一。由此产生的平均丰度比为1：1的正丙醇：异丙醇是一致的，从计算工作的结论，强相互作用的物种的几何取向是有影响力的程度，其中的“机制”参与，以及各种各样的几何形状导致平均的效果。实验中还初步鉴定了丙二醇的三种异构体。它也表明，丙烯和丙烷（H3CCHCH 2和H3CCH 2CH 3）是由H3CCCH加氢形成的。计算衍生的激活屏障提供了额外的洞察力，什么类型的反应和机制更可能发生在实验室和ISM中。我们的研究结果不仅表明，这里研究的醇共享共同的化学途径，因此可以同时出现在天文调查中，而且它们的扩展对应物，来自含有H3C（CC）nH结构的多炔可能存在于ISM中。这些较大的物种，如脂肪醇，是简单脂质的可能成分，早期地球上的原始细胞膜被认为是部分组成的。
英文摘要：
A number of recent experimental studies have shown that solid-state complex organic molecules (COMs) can form under conditions that are relevant to the CO freeze-out stage in dense clouds. In this work, we show that alcohols can be formed well before the CO freeze-out stage (i.e., in the H2O-rich ice phase). This joint experimental and computational investigation shows that the isomers, n- and i-propanol (H3CCH2CH2OH and H3CCHOHCH3) and n- and i-propenol (H3CCHCHOH and H3CCOHCH2), can be formed in radical-addition reactions starting from propyne (H3CCCH) + OH at the low temperature of 10 K, where H3CCCH is one of the simplest representatives of stable carbon chains already identified in the interstellar medium (ISM). The resulting average abundance ratio of 1:1 for n-propanol:i-propanol is aligned with the conclusions from the computational work that the geometric orientation of strongly interacting species is influential to the extent of which 'mechanism' is participating, and that an assortment of geometries leads to an averaged-out effect. Three isomers of propanediol are also tentatively identified in the experiments. It is also shown that propene and propane (H3CCHCH2 and H3CCH2CH3) are formed from the hydrogenation of H3CCCH. Computationally-derived activation barriers give additional insight into what types of reactions and mechanisms are more likely to occur in the laboratory and in the ISM. Our findings not only suggest that the alcohols studied here share common chemical pathways and therefore can show up simultaneously in astronomical surveys, but also that their extended counterparts that derive from polyynes containing H3C(CC)nH structures may exist in the ISM. Such larger species, like fatty alcohols, are the possible constituents of simple lipids that primitive cell membranes on the early Earth are thought to be partially composed of.
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