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Kita-ku, Japan

Oba Y.,N19W8 | Osaka K.,N19W8 | Watanabe N.,N19W8 | Chigai T.,N19W8 | Kouchi A.,N19W8
Faraday Discussions | Year: 2014

We performed laboratory experiments on the formation of water and its isotopologues by surface reactions of hydrogen peroxide (H2O 2) with hydrogen (H) atoms and their deuterated counterparts (D 2O2, D) at 10-30 K. High-purity H2O2 (>95%) was prepared in situ by the codeposition of molecular oxygen and H atoms at relatively high temperatures (45-50 K). We determined that the high-purity H2O2 solid reacts with both H and deuterium (D) atoms at 10-30 K despite the large activation barriers (∼2000 K). Moreover, the reaction rate for H atoms is approximately 45 times faster than that for D atoms at 15 K. Thus, the observed large isotope effect indicates that these reactions occurred through quantum tunneling. We propose that the observed HDO/H2O ratio in molecular clouds might be a good tool for the estimation of the atomic D/H ratio in those environments. This journal is © the Partner Organisations 2014.

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