Channeling effects in high-angular-resolution electron spectroscopy

Momentum-transfer-resolved electron spectroscopy is a technique for examining the electronic structure of materials and requires the use of detectors accepting a small range of momentum transfers. For crystalline specimens, it is necessary to consider the channeling behavior of the fast electrons both before and after inelastic scattering to adequately describe the signals produced. Using oxygen K -shell core loss in NiO as a case study, we examine channeling in high-angular-resolution electron-channeling electron spectroscopy. The roles of nonlocality and sample thickness as they relate to the channeling effect are explored. Particular attention is given to the behavior arising from the channeling of the scattered electrons, as compared with models in which only the incident electrons channel. Calculations allowing for the channeling of both the incident and the scattered electrons are computationally demanding and we explore approximations that can be made for detectors with small acceptance angles.