High energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) and Valence-to-Core X-ray emission (VtC-XES) spectroscopy are established as hard X-ray methods to investigate complexes that might be relevant as mimics for the biologically important Cu_A site. By investigation of three carefully selected complexes of the type [Cu₂(NGuaS)₂X₂], characterized by a cyclic Cu₂S₂ core portion and a varying adjunct ligand nature, it is proven that the HERFD-XANES and VtC-XES measurements in combination with extensive TD-DFT calculations can reveal details of the electronic states in such complexes, including HOMO and LUMO levels and spin states. By theoretical spectroscopy, the value of this methodic combination for future in situ studies is demonstrated.

中文翻译：

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仿生Cu ₂ S ₂配合物的实验和理论高能分辨率硬X射线吸收和发射光谱

建立高能分辨荧光检测的边缘结构附近的X射线吸收（HERFD-XANES）和价核心X射线发射（VtC-XES）光谱作为硬X射线方法，以研究可能与模拟物相关的复合物具有重要生物学意义的Cu _A位点。通过研究[Cu ₂（NGuaS）₂ X ₂ ]类型的三种精心选择的络合物，其特征是环状Cu ₂ S ₂核心部分和变化的辅助配体性质，已证明HERFD-XANES和VtC-XES测量与广泛的TD-DFT计算相结合，可以揭示此类复合物中电子态的详细信息，包括HOMO和LUMO能级以及自旋态。通过理论光谱学，证明了这种方法性组合对于将来的原位研究的价值。