同步辐射XANES方法对FeCl3 水溶液的研究

利用X 射线近边吸收谱学(X-ray Absorption Near Edge Structure, XANES)方法研究了不同浓度的FeCl₃ 水溶液中Fe³⁺离子的电子结构和近邻结构. 在不同浓度的FeCl₃ 水溶液的XANES 谱中, XANES 谱的形状随着FeCl₃ 浓度的不同而发生改变. 在XANES 谱的边前结构中观测到边前锋的分裂, 其分裂的能量差约为1.6 eV, 随着浓度的降低约有0.2 eV 的高能方向的位移, 此边前结构由1s-3d 轨道的电子跃迁引起, 双峰分裂来源于配位体配位引起的3d 轨道分裂. 随着FeCl₃ 浓度的改变, XANES 谱的主峰也发生变化, 此变化来源于溶液中Fe—Cl 配位与Fe—O 配位的比例变化. 另外, 利用量子化学计算的方法对于Fe³⁺与不同数目的H₂O 和Cl^?配位体络合时的构型进行了计算, 得到了Fe³⁺在水溶液中近邻结构的信息, 从另一方面解释了FeCl₃ 溶液中Fe³⁺离子3d 轨道分裂能的变化

Investigation of Fe~(3+) in FeCl_3 aqueous solution by XANES technique

Electron structures and local atomic structures of Fe³⁺ in different FeCl₃ aqueous solution have been studied by X-ray absorption near edge structure (XANES) technique. The result shows that XANES spectra are different when the concentration of FeCl₃ aqueous solution has been changed. Pre-edge regions of XANES spectra show a fine structure corresponding to a 1s to 3d transition of Fe atom, which is a double peak structure. Splitting energy of the double peak is about 1.6ev, and there is a 0.2ev shift to high-energy direction with concentration decreasing. Main peaks of XANES spectra of different FeCl₃ aqueous solution are different, which attribute to different proportion of Fe—Cl bonds and Fe—O bonds. A calculation of complex Fe³⁺ cation with different number of H₂O and Cl^? has been performed by computational method of quantum chemistry.