In transmission electron energy-loss spectroscopy, the cross section in 2D is quenched by kinematic effects once the momentum transfer becomes smaller than a critical value set by qz, the momentum loss parallel to the beam. Our highly momentum (Δq=0.02~\r{A}−1) and energy (ΔE=45~meV) resolved setup is instrumental on delivering the unprecedented experimental verification of quenched 2D EEL spectra on freestanding graphene at momentum transfers q below 0.06\r{A}−1. We retrieve the intrinsic uniform dielectric response of graphene from measured spectra by quantifying the kinematic suppression.
@article{arxiv.2406.02998,
title = {Direct observation of the vanishing EELS cross section in graphene},
author = {Alberto Guandalini and Ryosuke Senga and Yung-Chang Lin and Kazu Suenaga and Paolo Barone and Francesco Mauri and Thomas Pichler and Christian Kramberger},
journal= {arXiv preprint arXiv:2406.02998},
year = {2025}
}