Electron capture imaging of two-dimensional materials

Abstract

We demonstrate that electron transfer induced by fast ion impact can be used as an imaging technique of two-dimensional materials. Applied to a keV proton beam passing through a graphene surface, it is shown that coherent single-electron capture gives a sub-\aa{}ngstr\"om-scale spatial resolution image of the electronic structure of a single sheet. This imaging scheme is shown to be particularly effective, resolving missing atoms (vacancies) in the lattice, in a narrow projectile 5--10-keV energy region, where the capture probability exhibits a minimum at the center of the hexagonal cells. This geometry-dependent phenomenon is caused by the coupling dynamic between the initial state and a multi-electron entangled one-hole state and is therefore highly sample selective.