X射线驱动二氧化硅纳米表面上的三氢离子形成
X-ray Driven Trihydrogen Formation on Silica Nanosurfaces
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中文总结 AI 辅助
本研究通过1.88 keV X射线脉冲结合多种成像与光谱技术，证实水合二氧化硅纳米表面可通过表面电场驱动电荷转移形成$\boldsymbol{\rm H_3^+}$，确立了该机制在天体物理与表面催化间的统一性。
中文摘要 AI 辅助
三氢离子（$\boldsymbol{\rm H_3^+}$）是星际空间中构建分子复杂性的离子-分子反应的起始物，其经典形成反应$\boldsymbol{\rm H_2^+ + H_2 \rightarrow H_3^+ + H}$是否在辐射驱动电离下于无机表面发生，此前尚未得到验证。本研究采用强度为1.88 keV的X射线脉冲，在水合二氧化硅纳米颗粒上驱动$\boldsymbol{\rm H_3^+}$形成，结合离子速度图成像、电子飞行时间光谱及单粒子相干衍射成像技术，解析单个颗粒上的该化学反应。V/nm量级的自感生表面电场驱动界面电荷转移与水的碎片化，该电场是决定$\boldsymbol{\rm H^+}$、$\boldsymbol{\rm H_2^+}$及$\boldsymbol{\rm H_3^+}$相对产额的主导参数，且该产额随颗粒尺寸、组成及聚集状态变化。密度泛函理论与非绝热量子分子动力学模拟追踪了该电场驱动的电荷转移过程，其与半导体光电极的能带弯曲直接类似。这些结果确立了表面电场驱动的电荷转移，作为辐射主导的天体物理环境与电场驱动的表面催化之间的统一机制。
英文摘要
The trihydrogen cation ($\mathrm{H_3^+}$) initiates the ion-molecule reactions that build molecular complexity in interstellar space. Whether its canonical formation reaction, $\mathrm{H_2^+ + H_2 \rightarrow H_3^+ + H}$, proceeds on inorganic surfaces under radiation-driven ionization has remained untested. Here we drive $\mathrm{H_3^+}$ formation on hydrated silica nanoparticles using intense 1.88 keV X-ray pulses, combining ion velocity map imaging, electron time-of-flight spectroscopy, and single-particle coherent diffractive imaging to resolve this chemistry on individual particles. The self-induced surface electric field on the V/nm scale drives interfacial charge transfer and water fragmentation. This field is the dominant parameter governing the relative yields of $\mathrm{H^+}$, $\mathrm{H_2^+}$, and $\mathrm{H_3^+}$ across particle size, composition, and aggregation. Density functional theory and nonadiabatic quantum molecular dynamics simulations trace this field-driven charge transfer, directly analogous to band bending at semiconductor photoelectrodes. These results establish surface-field-driven charge transfer as a unifying mechanism between radiation dominated astrophysical environments and field-driven surface catalysis.
