Speaker
Description
At the neutron induced positron source Munich (NEPOMUC) at the MLZ, two analytical setups are being combined into a single system to enable positron surface studies with top-most layer sensitivity. The positron annihilation induced Auger-electron spectroscopy (PAES) instrument is being merged with the total reflection high-energy positron diffraction (TRHEPD) setup. The combination of those two positron techniques will enable highly surface sensitive elemental and structural analysis of the same sample under ultra-high vacuum (UHV) conditions. The PAES technique uses focused low-energy positrons that induce Auger-electron emission due to annihilation processes from the surface state. The corresponding Auger spectrum – without secondary electron background – provides elemental information on the top-most atomic layers and enables conclusions on fundamental as well as application-based research questions in surface science. As a highlight, atomic surface segregation was observed in situ with topmost layer sensitivity [1]. The TRHEPD technique [2] utilizes positron total reflection to enable surface sensitive diffraction [3]. Due to the high surface sensitivity, this technique allows for the study of surface reconstruction of the topmost atomic layers. With the combination of PAES and THREPD chemical as well as structural surface analysis will be possible on the same sample without exposing them to atmospheres. At the MLZ user meeting we would like to present a poster on the current merge plan of the PAES and TRHEPD instrument.
- J. Mayer, et al., Phys. Rev. Lett. 105 (2010) 207401
- M. Dodenhöft, et al., Rev. Sci. Instr. 92 (2021) 115103
- M. Dodenhöft, et al., Phys. Rev. B 108 (2023) 155438