A new near degeneracy effect for photoemission in transition metals

A previously neglected intra-atomic many-body effect has important consequences for the X-ray photoelectron spectra (XPS) of transition metal atoms and cations. This effect involves configurations where one elctron is promoted to a 4f orbital and another is dropped to fill the XPS hole; this can be viewed as a frustrated Auger configuration (FAC). The identification of this FAC is a major advance in the understanding of many-body effects in XPS. Its use affects the multiplet splitting and the absolute binding energy; it can also lead to new satellite structure. Furthermore, it is expected to be generally important.