Design and Application of a Relativistic Kramers-Kronig Analysis Algorithm

•Kramers–Kronig analysis relates low-loss EELS spectra to dielectric response theory.•Taking into account relativistic-loss modes is necessary for normal TEM conditions.•We first demonstrate how to simulate realistic low-loss EELS spectra.•These simulated spectra are processed with a relativistic Kramers–Kronig algorithm.•This optimized algorithm reveals the correct dielectric properties.•The results can be improved using regularization and processing hyperspectral data.