Determination of localized surface phonons in nanocrystalline silicon by inelastic neutron scattering spectroscopy and its application to deuterium isotope enrichment
Determination of localized surface phonons in nanocrystalline silicon by inelastic neutron scattering spectroscopy and its application to deuterium isotope enrichment
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DOI：
10.1103/physrevmaterials.5.066003
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发表时间：
2021-06
影响因子：
3.4
通讯作者：
Takahiro Matsumoto;Ikumi Nomata;T. Ohhara;Y. Kanemitsu
中科院分区：
文献类型：
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作者：
Takahiro Matsumoto;Ikumi Nomata;T. Ohhara;Y. Kanemitsu
氢（H）同位素氘（D）在硅（Si）半导体、硅微芯片和光纤的制造以及同位素标记化合物的合成方面引起了特别的兴趣。然而，以受控方式有效生产D或H氘化物是具有挑战性的，并且仍然缺乏合理的H同位素富集方案。在这里，我们展示了一个高效的交换反应，从H到D的纳米晶Si（n-Si）的表面上。通过将n-Si浸入稀D溶液中，成功地实现了D末端的四倍富集。通过使用非弹性中子散射光谱确定H-和D-终止的n-Si的表面局部振动模式，我们发现，负责这种富集的物理机制源于零点振荡能量和表面局部振动熵的差异。从理论上讲，使用气相反应可以大大提高富集程度（15倍）。这种富集方案避免了使用贵金属催化剂，为可持续的氢-重氢交换反应开辟了道路。
The hydrogen (H) isotope deuterium (D) has attracted special interest for the manufacture of silicon (Si) semiconductors, Si microchips, and optical fibers, as well as for the synthesis of isotopically labeled compounds. However, the efficient production of D or H deuteride in a controlled manner is challenging, and rational H isotope enrichment protocols are still lacking. Here, we demonstrate a highly efficient exchange reaction from H to D on the surface of nanocrystalline Si (n-Si). Fourfold enrichment of D termination was successfully achieved by dipping n-Si into a dilute D solution. By determining the surface-localized vibrational modes for H- and D-terminated n-Si using inelastic neutron scattering spectroscopy, we found that the physical mechanism responsible for this enrichment originates from the difference in the zero-point oscillation energies and entropies of the surface-localized vibrations. Theoretically, the extent of enrichment could be greatly enhanced (\ensuremath{\sim}15 times) using a gas-phase reaction. This enrichment protocol, which avoids the use of precious metal catalysts, opens the way for sustainable H-to-heavy H exchange reactions.