SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 31: Focus Session: Ion Beam Interaction with Surfaces and 2D Materials III
O 31.4: Vortrag
Dienstag, 28. März 2023, 11:30–11:45, GER 38
Charge exchange of highly charged ions scattered under grazing incidence — •Matthias Werl, Anna Niggas, Friedrich Aumayr, and Richard A. Wilhelm — TU Wien, Institute of Applied Physics, Vienna, Austria
When a highly charged ion approaches a surface, electrons are resonantly captured from the material, starting at distances of ≈ 10−25 Å above the surface. The electrons are captured into shells with n ≈ qin (qin: incident charge state), forming a hollow atom (HA) - a state where (mostly) high-n shells are populated. In the free case, these excited HAs would then decay via a combination of auto-ionization and radiative pathways, recharging the projectile in the process. At very close distances from a surface (dI ≤ 3 Å), another process, known as Interatomic Coulombic Decay (ICD), can take place. Here, the HA quickly decays to its ground state due to electron-electron scattering with electrons from the material.
To study the HAs and their free decay, neutralization via ICD is to be prevented. This can be achieved if the distance of closest approach is larger than dI, which happens at very grazing angles. Previous experiments showed that only a minor fraction of charged particles survive up to the detector under an incident angle of αinc = 1.6 ∘. Decreasing the incident angle even further (0.1 ∘ ≤ αinc ≤ 1.0 ∘), more charged particles are expected to arrive at the detector.
Here, we present our setup to achieve these small incident angles with an accuracy of ≈ ± 0.2 ∘ as well as first experimental results for the charge state distribution of the scattered projectiles.