Elementary Chemical Reaction at Ultralow Temperature

超低温基本化学反应

基本信息

批准号：
60470008
负责人：
MIYAZAKI Tetsuo
金额：
$ 2.75万
依托单位：
Faculty of Engineering, Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

Basic to any theory of elementary chemical reactions is an understanding of the simplest atom-diatomic molecule exchange reaction of <H_2> (or <D_2> or HD). The role of a quantum-mechanical tunneling effect of the <H_2> + H reaction has been one of the important problems in the theory of chemical kinetics. Since the previous studies have been undertaken above 200 K, it was difficult to discriminate clearly between the reaction caused by the quantum-mechanical tunneling effect and the reaction which proceeds by passing over a potential energy barrier.In order to clarify the tunneling effect, Miyazaki has studied the <H_2> (or HD or <D_2> ) + D(or H) reaction in the radiolysis of solid hydrogen at 4.2 and 1.9 K by ESR spectroscopy. The following results were obtained. (1) The fast decay of H atoms in solid <H_2> was explained by a model of tunneling migration in which the H atoms repeat tunneling abstraction reactions with <H_2> ( <H_2> + H -> H + <H_2> ) and migrate through solid <H_2> to recombine with other H atoms. (2) A direct evidence for tunneling reaction HD + D -> H + <D_2> was obtained in the radiolysis of a <D_2> -HD mixture. (3) The rate constants for tunneling reactions of HD + D -> H + <D_2> and <D_2> + D -> D + <D_2> were measured.Recoil tritium reaction in rare gas-ethane solid mixtures has been studied at 11 - 20 K. It was found that tritium atoms react with ethane by quantum tunneling.Mechanism of paired radical formation in the radiolysis of solid methane has been studied by ESR spectroscopy at 4.2 K. Ionic fragmentation was observed in the radiolysis of rare gas-alkane mixtures at 4.2 K. The initial energy of hot H atoms produced by the radiolysis of alkane was estimated by ESR spectroscopy at 4.2 K.

任何基本化学反应理论的基础都是理解最简单的原子-双原子分子交换反应 <H_2>（或 <D_2> 或 HD）。 <H_2>+H反应的量子力学隧道效应的作用一直是化学动力学理论中的重要问题之一。由于之前的研究都是在200K以上进行的，很难清楚地区分量子力学隧道效应引起的反应和跨越势能垒进行的反应。为了澄清隧道效应，宫崎骏通过ESR光谱研究了4.2和1.9 K下固体氢辐射分解中的<H_2>（或HD或<D_2>）+D（或H）反应。得到以下结果。 (1) 固体<H_2>中H原子的快速衰变可以通过隧道迁移模型来解释，其中H原子与<H_2>重复发生隧道夺取反应(<H_2>+H->H+<H_2>)并且迁移通过固体<H_2>与其他H原子重新结合。 (2)在<D_2>-HD混合物的辐射分解中获得了隧道反应HD+D→H+<D_2>的直接证据。 (3)测量了HD+D→H+<D_2>和<D_2>+D→D+<D_2>隧道反应的速率常数。稀有气体-乙烷固体混合物中反冲氚反应的研究11 - 20 K。发现氚原子通过量子隧道效应与乙烷反应。通过ESR光谱在4.2研究了固体甲烷辐射解中成对自由基形成的机理。 K. 在 4.2 K 的稀有气体-烷烃混合物的辐射分解中观察到离子碎裂。通过 ESR 光谱在 4.2 K 估算烷烃辐射分解产生的热 H 原子的初始能量。