New Developments in Theory of X-ray Photoemission from Solids

In this review article we discuss some new developments in photoemission theories. We first discuss basic theoretical framework on the basis of quantum electrodynamics (QED), which allows us to treat radiation field screening from first principle theory. Based on this theoretical framework, recent theoretical developments in x-ray photoemission theories are reviewed, which have rarely been discussed in the previous review articles. Topics selected in this review article are multi-atom resonant photoemission (MARPE), anomalous behavior of the L23-edge intensity ratio of 3d transition metals, high-energy photoemission in particular non-dipole effects and recoil exciting phonon around the x-ray absorbing atom, and relativistic and magnetic effects.