Local electronic structural analysis of liquid solutions by soft X-ray spectroscopy

软x射线吸收光谱（XAS）是一种研究液体和水溶液局部电子结构的元素选择性方法。然而，在传输模式下测量XAS是困难的，因为软x射线被溶剂强烈吸收。在本研究中，我们开发了一种传输型液流池，其液层厚度可控在20 ~ 2000 nm之间，并成功测量了液体和水溶液在传输模式下的XAS。用XAS揭示了几种水溶液（如甲醇-水二元溶液）在C、N和O k边的局部结构。通过对传动型液流电池的改进，我们开发了一种原位XAS测量系统，用于研究催化和电化学反应中溶液的局部电子结构变化。

Soft X-ray absorption spectroscopy (XAS) is an element-selective method to investigate local electronic structures of liquid and aqueous solutions. However, the measurement of XAS in transmission mode is difficult because soft X-rays are strongly absorbed by solvents. In this study, we have developed a transmission-type liquid flow cell, in which the thickness of the liquid layer is controllable between 20 and 2000 nm, and successfully measured XAS of liquid and aqueous solutions in transmission mode. The local structures of several aqueous solutions such as methanol-water binary solutions are revealed by XAS in C, N, and O K-edges. We have also developed an in situ XAS measurement system to study local electronic structural changes of solutions in catalytic and electrochemical reactions by improving the transmission-type liquid flow cell.