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O: Fachverband Oberflächenphysik
O 71: Electronic Structure of Surfaces I
O 71.6: Vortrag
Mittwoch, 18. März 2020, 16:30–16:45, REC C 213
Orbital imaging: Sparsity-driven phase retrieval of angular-resolved photoemission spectroscopy data — •Matthijs Jansen1, Marius Keunecke1, Marten Düvel1, Christina Möller1, David Schmitt1, Wiebke Bennecke1, Jasmin Kappert1, Daniel Steil1, Russell Luke2, Sabine Steil1, and Stefan Mathias1 — 11st Physical Institute, University of Göttingen, Göttingen — 2Institute for Numerical and Applied Mathematics, University of Göttingen, Göttingen
In recent years, iterative phase retrieval of angle-resolved photoemission spectroscopy (ARPES) has attracted interest as a method to visualize molecular orbitals in molecule-metal interfaces. This method, dubbed orbital imaging, relies on prior knowledge of the investigated orbital. So far, successful orbital imaging has been based on the support constraint, for which the shape of the orbital must be known.
We will present a sparsity-driven approach to phase retrieval, which uses only the number of non-zero pixels in the orbital. This sparsity constraint is easy to determine and independent of the orbital shape. Additionally, we include symmetry in the phase retrieval approach. We apply the resulting phase retrieval algorithms successfully to both simulated and experimental ARPES data, acquired using a so-called momentum microscope, which uses time-of-flight-based detection to measure the full momentum and energy-dependent spectrum in a single measurement. This enables us to image multiple molecular orbitals simultaneously. We conclude that sparsity-driven phase retrieval requires less prior knowledge to achieve good orbital imaging results.