Dresden 2026 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 93: Electronic structure of surfaces: Spectroscopy, surface states III

O 93.9: Vortrag

Freitag, 13. März 2026, 11:30–11:45, HSZ/0201

3D Mapping of Photoelectron Diffraction Patterns at Very Low Energies — •O. Tkach¹, T.-P. Vo², D. Biswas³, J. Liu³, O. Fedchenko^1,4, T.-L. Lee³, J. Minár², H.-J. Elmers¹, and G. Schönhense¹ — ¹Univ., Mainz — ²Univ. of West Bohemia, Czech Republic — ³Diamond Light Source, UK — ⁴Goethe Univ. Frankfurt

The full-field recording architecture of momentum microscopes (MMs) efficiently captures the (E,k) valence band structure along with the corresponding dichroism and spin texture [1]. Here, we apply the same approach to photoelectron diffraction (PED) in the low-energy range. Capturing PED in a solid angle up to 2π, including the corresponding core-level CDAD [2] reveals a wealth of structure far beyond that of standard PED measurements. The experiments are compared with calculated three-dimensional (E,k_x,k_y) patterns obtained via one-step photoemission calculations using the PED implementation [3] within the SPRKKR package. Calculated results over a wide range of kinetic energies (106 − 1036 eV) for the Ge 3d core level reveal striking patterns that change rapidly with photon energy. The high-energy end provides insight into bulk (Kikuchi-) diffraction, while the lower end with its high surface sensitivity yields structural information about the surface. This is indicative of the transition from a localized core level to an itinerant, time reversed LEED photoemission final state. In general, these results bridge the gap between PED analysis and electronic structure investigations.
[1] Medjanik et al. Nat. Mater 16, 615 (2017); [2] Tkach et al. Ultramic. 250, 113750(2023); [3]Vo et al. npj Comput. Mater.11, 159(2025)

Keywords: Photoelectron diffraction; CDAD; Momentum microscopy; One-step photoemission calculations