真空中固液界面的离子束分析研究

Study on the Solid-liquid Interface Using Ion Beam Analysis in Vacuum

原位实时地高精度测量固液界面的元素或离子(电荷)组成和动态变化对于界面反应和相互作用研究非常重要,但是传统的高分辨离子束分析实验在真空环境中不能直接测量液体样品。本文研制了一种固体-液体界面探针,该探针使用氮化硅-铝纳米复合膜作为真空密封窗和电化学电极,利用复旦大学核微探针成功开展了真空中固体-液体界面探针0.01 mol/L氯化钡和1 mol/L氯化镧溶液样品固体-液体界面的卢瑟福背散射(RBS)分析和粒子激发X射线(PIXE)分析。实验结果表明,真空环境下,固液界面探针纳米薄窗可承受2 MeV He+离子注量为1.0×1018 ions/cm2的辐照。微区PIXE分析成功获得了固液界面探针结构的元素分布。通过对卢瑟福背散射能谱进行分析,获取了20 nm分辨的电极界面微米深溶液中的La, Cl元素浓度。在1 mol/L的LaCl3固液界面电极表面,负电压(–2.3 V)时电解质离子在电极表面高浓度聚集,正电压(+2.3 V)时电解质在电极表面呈低浓度分布,在约1 250 nm深处电解质溶液趋向于体浓度。

The in-situ and real-time high-precision measurement of the composition and dynamic change of elements or ions(charges) at the solid-liquid interface with nano-to-micron thickness is very important in the understanding of the interface interaction and reaction, while traditional high-resolution ion beam analysis can not directly measure liquid samples in vacuum environment. In this paper, a solid-liquid interface probe in vacuum was developed. The probe used Si3N4-Al nanocomposite membrane as vacuum sealing window and electrochemical electrode. The Rutherford Backscattering Spectroscopy(RBS) analysis and particle-induced X-ray Emission(PIXE)analysis with the solid-liquid interface probes of 0.01 mol/L BaCl2 and 1 mol/L LaCl3 solution were successfully carried out using Fudan University nuclear microprobe. The experimental results show that the nano-window of solidliquid interface probe can withstand the irradiation of 2 MeV He+ ions with a dose of 1.0×1018 ions/cm2 in vacuum. The distribution of structure elements in solid-liquid interface probes was successfully obtained by PIXE analysis. The concentration of La and Cl in micron deep solution of electrode interface was obtained by Rutherford backscattering analysis with 20-nm-resolution. On the surface of 1 mol/L LaCl3 solid-liquid interface electrode, electrolyte ions accumulated at a high concentration at negative voltage(–2.3 V), while electrolyte ions distributed at a low concentration at positive voltage(+2.3 V), and electrolyte solutions tended to bulk concentration at a depth of about 1 250 nm.