Abstract X-ray photoelectron spectroscopy (XPS) was employed to characterize the surface composition, atoms’ chemical state and electronic structure of oxalates MeC2O4·nH2O (Me = Mn, Fe, Co, Ni, Cu); their structure was characterized by XRD. Core-level Me 2p, Fe 3p, Fe 3s, C 1s, O 1s, X-ray induced Auger Me LMM, O KVV and valence band spectra are presented along with a number of parameters derived from the spectra analysis. A comparative analysis of FeC2O4 and Fe2(C2O4)3 oxalates is performed. The XPS parameters for the oxalates are compared to those for respective oxides. Variation of spin-orbit splitting, multiplet splitting, energy separation and intensity of satellites in the Me 2p spectra across the series of the compounds is considered in terms of changes in the electronic structure and strength of the Me–O bonding. The strong effect of covalency of the ligand (C2O42– vs. O2–) is demonstrated. Auger parameters α′(Me) and α′(O) are determined and used for estimating the initial state effects in photoemission. The surface charging of the oxalates is shown to be mainly dependent on the surface composition and stoichiometric atomic ratios. In the C 1s and O 1s spectra of the oxalates, intense satellites are revealed for the first time.

中文翻译：

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过渡金属草酸盐的 XPS 表征

摘要 采用X射线光电子能谱(XPS)表征草酸盐MeC2O4·nH2O(Me=Mn、Fe、Co、Ni、Cu)的表面组成、原子化学状态和电子结构；它们的结构通过XRD表征。展示了核心级 Me 2p、Fe 3p、Fe 3s、C 1s、O 1s、X 射线诱导的俄歇 Me LMM、O KVV 和价带光谱以及从光谱分析得出的许多参数。对 FeC2O4 和 Fe2(C2O4)3 草酸盐进行了比较分析。将草酸盐的 XPS 参数与相应氧化物的参数进行比较。根据 Me-O 键的电子结构和强度的变化，考虑了一系列化合物的 Me 2p 光谱中卫星的自旋轨道分裂、多重分裂、能量分离和强度的变化。证明了配体（C2O42– 与 O2–）共价的强烈影响。确定了俄歇参数 α'(Me) 和 α'(O) 并用于估计光发射中的初始状态效应。草酸盐的表面电荷主要取决于表面组成和化学计量原子比。在草酸盐的 C 1s 和 O 1s 光谱中，首次揭示了强烈的卫星。