ESR study of atomic hydrogen and tritium in solid T2 and T2:H2 matrices below 1 K.
ESR study of atomic hydrogen and tritium in solid T2 and T2:H2 matrices below 1 K.
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1 K 以下固体 T2 和 T2:H2 基体中原子氢和氚的 ESR 研究。
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
V. Khmelenko
中科院分区：
文献类型：
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作者：
S. Sheludiakov;J. Ahokas;J. Järvinen;L. Lehtonen;Olli Vainio;S. Vasiliev;David M. Lee;V. Khmelenko
我们首次报道了氢原子和氚原子在固体T2和T2：H2中稳定到70mK的ESR研究。T原子在T2中的浓度接近2×10~(20)cm~(-3)(0.60%)，而H原子在T_2：H_2固体混合物中的浓度达到创纪录的1×10~(20)cm~(-3)(0.33%)。由于T原子和H原子之间的同位素交换反应T+H2∼TH+H，T原子和H原子的最大浓度受到它们复合的限制。由于β粒子在基质中产生大量空位和声子，这种复合增强了T原子和H原子的有效扩散。复合也以爆炸性的方式出现，在样品冷却不足的厚膜中既被刺激又自发地出现。我们认为，H和T迁移的主要机制是与隧穿或跳跃到空位有关的物理扩散，而隧穿化学交换反应控制了通过其他方法在H2和D2基质中产生的H和D原子的扩散。
We report on the first ESR study of atomic hydrogen and tritium stabilized in solid T2 and T2:H2 matrices down to 70 mK. The concentrations of T atoms in pure T2 approached 2 × 1020 cm-3 (0.60%) and record-high concentrations of H atoms ∼1 × 1020 cm-3 (0.33%) were reached in T2:H2 solid mixtures where a fraction of T atoms became converted into H due to the isotopic exchange reaction T + H2 → TH + H. The maximum concentrations of unpaired T and H atoms were limited by their recombination which becomes enhanced by efficient atomic diffusion due to the presence of a large number of vacancies and phonons generated in the matrices by β-particles. Recombination also appeared in an explosive manner, both being stimulated and spontaneously in thick films where sample cooling was insufficient. We suggest that the main mechanism for H and T migration is physical diffusion related to tunneling or hopping to vacant sites in contrast to tunneling chemical exchange reactions which govern diffusion of H and D atoms created in H2 and D2 matrices by other methods.