LABORATORY EVIDENCE FOR EFFICIENT WATER FORMATION IN INTERSTELLAR ICES
LABORATORY EVIDENCE FOR EFFICIENT WATER FORMATION IN INTERSTELLAR ICES
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DOI：
10.1086/591506
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发表时间：
2008-10-20
影响因子：
4.9
通讯作者：
Linnartz, H.
中科院分区：
文献类型：
--
作者：
Ioppolo, S.;Cuppen, H. M.;Linnartz, H.
尽管水是星际冰地幔的主要成分，但其化学起源还没有得到很好的理解。三种不同的形成途径已经提出了以下的O，O-2，或O-3的氢化冰颗粒，但实验证据在很大程度上是缺乏的。我们提出了一个固态天体化学实验室的研究，这些路线之一进行测试。为此目的，在12 K至28 K的天文学相关温度下，在真空条件下用H或D原子轰击O-2冰。使用反射吸收红外光谱法（RAIRS）允许反应速率的推导，并显示出H2O（D2 O）的有效形成，其速率令人惊讶地与温度无关。这种形成路线通过H2 O2将O-2转化为H2O，并且被发现比先前假设的效率高出几个数量级。因此，它应该被认为是一个重要的通道，星际水冰形成所示的天体化学模型计算。
Even though water is the main constituent in interstellar icy mantles, its chemical origin is not well understood. Three different formation routes have been proposed following hydrogenation of O, O-2, or O-3 on icy grains, but experimental evidence is largely lacking. We present a solid state astrochemical laboratory study in which one of these routes is tested. For this purpose O-2 ice is bombarded by H or D atoms under ultrahigh vacuum conditions at astronomically relevant temperatures ranging from 12 to 28 K. The use of reflection absorption infrared spectroscopy (RAIRS) permits derivation of reaction rates and shows efficient formation of H2O(D2O) with a rate that is surprisingly independent of temperature. This formation route converts O-2 into H2O via H2O2 and is found to be orders of magnitude more efficient than previously assumed. It should therefore be considered as an important channel for interstellar water ice formation as illustrated by astrochemical model calculations.