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O: Fachverband Oberflächenphysik
O 93: Electronic structure of surfaces: Spectroscopy, surface states III
O 93.1: Vortrag
Freitag, 13. März 2026, 09:30–09:45, HSZ/0201
Identifying Electronic Doorway States in Secondary Electron Emission — •Anna Niggas1, Maosheng Hao2, Peter Richter3, Felix Blödorn1, Florian Simperl1, Alessandra Belissimo4, Joachim Burgdörfer2, Thomas Seyller3, Wolfgang Werner1, Florian Libisch2, and Richard A Wilhelm1 — 1Institute of Applied Physics, TU Wien, Vienna, Austria — 2Institute for Theoretical Physics, TU Wien, Vienna, Austria — 3Institute of Physics, Chemnitz University of Technology, Chemnitz, Germany — 4Institute of Photonics, TU Wien, Vienna, Austria
Secondary electron emission following low-energy (<200 eV) electron impact is fundamental to particle-solid interactions but remains incompletely understood. While high-energy electrons are described by reflected primaries undergoing inelastic losses, the low-energy (<20 eV) region is often considered featureless. Coincidence spectroscopy has revealed hidden structures, notably the 3.3 eV X peak in graphite arising from plasmon excitation and interlayer-state hybridisation. Following that, we have measured low-energy secondary electrons from graphite and quasi-freestanding single- and bilayer graphene, enabling a controlled transition from bulk to two-dimensional systems. We observe layer-dependent features and, supported by density functional theory, attribute them to Feshbach-type resonances of quasi-bound above-vacuum states coupling to the continuum. The strong 3.3 eV resonance appears only in systems with five or more layers [1].
[1] A. Niggas et al., Phys. Rev. Lett. 135, 166401 (2025)
Keywords: secondary electron emission; coincidence spectroscopy; plasmons; graphite; graphene