Electron emission from a freestanding single layer of graphene due to highly charged ion impact

Abstract

When a slow highly charged ion (HCI) strikes a surface, its potential energy is dissipated - partly through electron emission - within a few femtoseconds [1]. In the case of HCIs interacting with 2D materials, it is not yet known on which side the electrons are emitted, in front or behind the impinged surface. We investigate this by measuring electron emission from both sides of a freestanding single- layer graphene target irradiated with slow Xe30+ ions. By detecting secondary electrons in coincidence with the transmitted ion, electron yields are correlated with ion neutralization and kinetic energy loss during the interaction. Preliminary data reveal the emission of up to 60 electrons per ion impact from each side of the graphene layer. Where the ion enters (entrance side), the electron yield correlates with ion neutralization: more electrons captured by the ion lead to more emitted electrons. Exit-side emission, however, appears largely independent of neutralization. These findings suggest different emission mechanisms on each side and may shed light on the spatial and temporal dynamics of ultrafast HCI-surface interactions. References [1] A. Niggas et al. Phys. Rev. Lett. 129 086802 (2022)