星际冰中有效水形成的实验室证据
Laboratory evidence for efficient water formation in interstellar ices
摘要：
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被提出以下的O，O2，或O3的氢化，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，在超高真空条件下，在12至28 K的天文学相关温度下，用H或D原子轰击O2冰。使用反射吸收红外光谱法（RAIRS）可以推导出反应速率，并显示出H2O（D2O）的有效形成，其速率令人惊讶地与温度无关。该形成路线通过H2O2将O2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。
英文摘要：
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, O2, or O3, 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 O2 ice is bombarded by H- or D-atoms under ultra high 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 O2 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.
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