Infrared Spectroscopic Studies of Oxygen Atom Quantum Diffusion in Solid Parahydrogen
Infrared Spectroscopic Studies of Oxygen Atom Quantum Diffusion in Solid Parahydrogen
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固体仲氢中氧原子量子扩散的红外光谱研究
DOI：
10.1021/acs.jpca.3c00266
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Anderson, David T.
中科院分区：
文献类型：
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作者：
Muddasser, Ibrahim;Nguyen, Anh H.;Strom, Aaron I.;Hardee, Aaron M.;Pluid, Bryan G.;Anderson, David T.
20 世纪 90 年代，人们对稀有气体基质中原子种类的热诱导扩散进行了广泛研究，以研究低温固态反应并合成反应中间体。相比之下，人们对固体仲氢 (p-H2) 等量子固体中原子种类的扩散知之甚少。虽然氢原子早在 1989 年就已在 4.2 K 下在普通氢固体中扩散，但其他原子种类在固体 p-H2 中的扩散尚未在文献中报道。本文研究了通过 ArF 激光在 193 nm 波长下照射 O2 掺杂的 p-H2 固体来产生原子氧，以研究 O(3P) 原子在量子固体中的扩散。通过 O3 反应产物的红外光谱测量光解后 O(3P) + O2→ O3 反应的动力学来检测 O(3P) 原子迁移率。该反应是无垒的，因此假定在这些条件下是扩散控制的，使得反应速率常数可用于估计氧原子扩散系数。 O3 增长曲线与单指数表达式很好地拟合，允许提取 O(3P) + O2→ O3 反应的伪一阶速率常数。反应速率受 p-H2 晶体形态的强烈影响，并表现出与 O(3P) 原子的量子扩散一致的非阿伦尼乌斯型温度依赖性。实验结果与 p-H2 中的 H(2S) 原子反应研究、稀有气体基质中的类似研究以及天文冰和表面中原子扩散的实验室研究进行了比较。
The thermally induced diffusion of atomic species in noble gas matrices was studied extensively in the 1990s to investigate low-temperature solid-state reactions and to synthesize reactive intermediates. In contrast, much less is known about the diffusion of atomic species in quantum solids such as solid parahydrogen (p-H2). While hydrogen atoms were shown to diffuse in normal-hydrogen solids at 4.2 K as early as 1989, the diffusion of other atomic species in solid p-H2has not been reported in the literature. Thein situphotogeneration of atomic oxygen, by ArF laser irradiation of an O2-doped p-H2solid at 193 nm, is studied here to investigate the diffusion of O(3P) atoms in a quantum solid. The O(3P) atom mobility is detected by measuring the kinetics of the O(3P) + O2→ O3reaction after photolysis via infrared spectroscopy of the O3reaction product. This reaction is barrierless and is thus assumed to be diffusion-controlled under these conditions such that the reaction rate constant can be used to estimate the oxygen atom diffusion coefficient. The O3growth curves are well fit by single exponential expressions allowing the pseudo-first-order rate constant for the O(3P) + O2→ O3reaction to be extracted. The reaction rates are affected strongly by the p-H2crystal morphology and display a non-Arrhenius-type temperature dependence consistent with quantum diffusion of the O(3P) atom. The experimental results are compared to H(2S) atom reaction studies in p-H2, analogous studies in noble gas matrices, and laboratory studies of atomic diffusion in astronomical ices and surfaces.