Reaction kinetics and isotope effect of water formation by the surface reaction of solid H2O2 with H atoms at low temperatures
Reaction kinetics and isotope effect of water formation by the surface reaction of solid H2O2 with H atoms at low temperatures
复制标题
低温下固体H2O2与H原子表面反应生成水的反应动力学和同位素效应
DOI：
10.1039/c3fd00112a
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
A. Kouchi
中科院分区：
文献类型：
--
作者：
Y. Oba;K. Osaka;N. Watanabe;T. Chigai;A. Kouchi
我们在实验室中研究了过氧化氢(H_2O_2)与氢原子(H_2O_2，D_2O_2)在10~30K下的表面反应生成水及其同位素聚合物。在相对较高的温度(45~50K)下，通过分子氧和氢原子的共沉积原位制备了高纯度的H_2O_2(>；95%)。我们确定，尽管存在很大的活化势垒(∼2000K)，但高纯度的H_2O_2固体在10-30 K与氢原子和氢原子(D)反应。此外，在15K下，H原子的反应速率约为D原子的45倍。因此，观察到的大同位素效应表明，这些反应是通过量子隧道进行的。我们认为，在分子云中观测到的HDO/H2O比可能是估算这些环境中原子D/H比的一个很好的工具。
We performed laboratory experiments on the formation of water and its isotopologues by surface reactions of hydrogen peroxide (H2O2) with hydrogen (H) atoms and their deuterated counterparts (D2O2, 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.