Vortrag im Rahmen der Chemisch Physikalischen Gesellschaft
What sets ion beams apart from experiments with electrons, neutrons, or photons is an additional parameter besides the (kinetic) energy, which can be independently varied: By removing more and more electrons from an initially neutral atom, a potential energy is stored. For highly charged ions, e.g., Xe40+, this potential energy can reach up to 40 keV and – in the case of very slow projectiles – may even exceed the amount of available kinetic energy in the interaction process with a sample.
Upon approaching a material surface, slow highly charged ions deposit their potential energy within the very first layers of a material, leading to the neutralisation of the projectile and the emission of secondary electrons and photons. Using two-dimensional materials as targets in transmission geometry, we can now investigate not only this secondary particle emission but also detect the projectiles themselves after the interaction. For these experiments, we apply a coincidence spectroscopy technique, i.e. we measure correlated pairs of transmitted ions and emitted electrons, allowing us to unravel complex charge exchange processes. In this presentation, I will discuss how fast the neutralisation of a slow (highly charged) ion happens within the material and how different electronic sample properties may influence these dynamics.
