Slow highly charged ions for probing two-dimensional materials
by Janine Schwestka (IAP TU Wien)
at GSI ( GSI Lecture Hall - Side Room )
The potential energy an ion is carrying, initially stored during its production process, can add up to several 10 keV for ions in very high charge states (e.g. Xe ions in charge states >30) and even exceed its kinetic energy. When using very slow ions (<100 keV), this high amount of potential energy is released already within the first few layers of a material upon target impact. We perform ion transmission studies of highly charged projectiles through ultimately thin (one up to only a few atomic layers) films, where the energy deposition within the first layer becomes crucial. In the case of these two-dimensional targets, the neutralization process of the ion is not fully completed and the projectile remains charged after the transmission. This allows us to study fundamental charge exchange processes of highly charged ions with different target materials. We measure the exit charge state of the ion after the transmission, the energy loss of the ion within the target as well as the released energy by emission of low energy electrons. In this way, we probe the electronic response of two-dimensional materials to ultrafast external perturbations, which is nowadays of great interest for the development of novel devices (e.g. in the field of optoelectronics).
 E. Gruber et al., Nat. Commun. 7 (2016) 13948.