Valence band dispersion embedded in resonant Auger electrons

Resonant photoelectron spectroscopy highlights certain elemental components of the valence band by adjusting the photon energy to a core-level excitation threshold, allowing the study of the element-specific density of states. However, most of the investigations to date have focused on one-dimensional spectral analysis. Thus, we investigated the conditions for transiting the valence band momentum information to Auger electrons using two-dimensional momentum-resolved photoemission measurements. We identified four different types of resonant pathways of the core and valence states at the C K-shell absorption threshold from single-crystal graphite. This includes a participant Auger process that enhances direct valence band emission, spectator Auger processes with Dirac cone shakeup excitations, and a novel dispersion structure that overlaps with the normal Auger electron kinetic energy region. In this study, we discuss the mechanism by which these band dispersions are embedded in the resonant photoelectron and Auger electron emission processes. (author)