Spatial Resolution in Electron Energy-Loss Spectroscopy

The combination of electron energy-loss measurements (EELS) and corresponding ab initio calculations has been very productive for the study of collective electronic excitations (plasmons) in solids and nano objects. While most of these investigations have been angular resolved, new techniques allow for atomic spatial resolution (e.g. the UltraSTEM microscope at the LPS, Orsay, France) and call for corresponding theoretical investigations. First, we have studied the spatial distribution of excitations (plasmons) in Carbon systems using ab initio calculations [1] within the framework of time-dependent density functional theory (TDDFT). Second, we present an approach to study spatially resolved EELS in the low loss region (less than 40 eV), explicitly taking into account for non-local effects of the dielectric function. [1] DP-code: http://www.dp-code.org; V.Olevano et.al., unpublished.