Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 59: 2D Materials III: Nanomembranes, hBN, and Particle Interactions
O 59.8: Vortrag
Mittwoch, 3. April 2019, 17:00–17:15, H16
Unraveling energy-loss processes of low energy heavy ions in 2D materials — •Richard A. Wilhelm1,2 and Pedro L. Grande3 — 1TU Wien, Institute of Applied Physics, Austria — 2HZDR, Institute of Ion Beam Physics and Materials Research, Germany — 3Federal University of Rio Grande so Sul, Institute of Physics, Ion Implantation Laboratory, Brazil
In order to use ion beams for defect engineering of 2D materials, a model for energy deposition is needed, which takes the ion charge state and charge exchange into account. In the first monolayers of a material impinging keV ions capture electrons and reduce their charge state until charge equilibrium is reached in less than 10 fs (about 1 nm).
We present here a new model for charge state and charge exchange dependent ion stopping force calculation, which shows that heavy ions in charge states greater than 1 deposit a substantially larger amount of their kinetic energy in a 2D material than predicted by standard tools as e.g. SRIM. This holds true for electronic and nuclear energy losses, whereas especially the latter causes sputtering and therefore structural defects.
Our model relies an a time-dependent scattering potential, which changes due to charge exchange and electronic de-excitation of the projectile during collision. We compare our model results with experimental values determined by heavy highly charged ion transmission through freestanding single layer graphene and find very good agreement in energy loss, charge state distributions, and scattering angle-dependent charge exchange.