High Energy Spectroscopy in f and d Electron Systems

该项目的目的是通过日本和欧洲代表性研究人员的合作，发展“高能光谱”的理论和实验研究，如x射线吸收光谱（XAS）和x射线光电发射光谱（XPS）。共同研究的主要成果如下：对于重稀土和过渡元素的浅层核能级，发现XPS终态寿命具有很强的多项依赖性。通过这一发现，解决了稀土4d XPS和过渡元素3p XPS解释中长期存在的问题（贡献者：Kotani， Okada， Thole和Sawatzky）。上述项相关寿命的影响在x射线发射光谱中也很重要。这方面的理论和实验研究目前正在进行中（Kotani, Tanaka， Parlebas和Shin）。通过分析XPS和XAS数据，对轻过渡金属氧化物的电子态进行了系统的研究。3 .指出过渡元素3d和氧2p之间存在很强的共价杂化（Kotani, Okada, Shin， Palebas和Steiner）。通过对CePd_7的XAS和XPS分析，发现了异常强的价态混合。同时，CePd_7表面的Ce离子处于三价态（Kotani, Parlebas， Shin和Fujimori）。用XAS和XPS研究了LaCoO_3中三个高自旋-低自旋跃迁。通过簇模型和带模型进行了理论分析（Fujimori， Abbate和Sawatzky）。关于铁磁材料XAS中的磁性x射线二色性，交换了新的信息（Jo, van der Laan， Thole和Carra）。

The purpose of this project is to develop both theoretical and experimental studies of "high energy spectroscopy", such as X-ray absorption spectroscopy (XAS) and X-ray photoemission spectroscoppy (XPS), by the collaboration of representative Japanese and European researchers. The main results of the joint research are as follows :1. For shallow core levels of heavy rare-earths and transition elements, it is revealed that the lifetime of final states of XPS has a strong multiplet-term-dependence. By this finding, long-standing problems in the interpretation of rare-earths 4d XPS and transition element 3p XPS are resolved (contributors : Kotani, Okada, Thole and Sawatzky).2. The effect of the term-dependent lifetime mentioned above is also important in X-ray emission spectroscopy (XES). Both theoretical and experimental studies along this line is now in progress (Kotani, Tanaka, Parlebas and Shin).3. Systemetic study of electronic states of light transition-metal oxides has been performed by analysing XPS and XAS data. The existence of very strong covalency hybridization between transition element 3d and oxygen 2p is pointed out (Kotani, Okada, Shin, Palebas and Steiner).4. Anomalously strong valence-mixing is found from the analysis of XAS and XPS of CePd_7. At the same time, the surface Ce ion in CePd_7 is in the trivalent state (Kotani, Parlebas, Shin and Fujimori).5. Tre high spin-low spin transition in LaCoO_3 is studied by XAS and XPS.Theoretical analyzes by a cluster model and a band model are also performed (Fujimori, Abbate and Sawatzky).6. On magnetic X-ray dichroism in XAS of ferromagnetic materials, the exchange of new information has been made (Jo, van der Laan, Thole and Carra).