ABSTRACT
In Chapter 2, we used the single electron excitation description of x-ray absorption and the other core level spectroscopies. However, in the core level spectroscopies of strongly correlated electron systems, such as rare earth (RE) systems and transition metal (TM) compounds, the single electron excitation picture often breaks down. The many-body effects beyond the single electron excitation are mainly divided into the charge-transfer effect and the intra-atomic multiplet coupling effect.
