TY  - JOUR
A1  - Kern, Christian S.
A1  - Haags, Anja
A1  - Egger, Larissa
A1  - Yang, Xiaosheng
A1  - Kirschner, Hans
A1  - Wolff, Susanne
A1  - Seyller, Thomas
A1  - Gottwald, Alexander
A1  - Richter, Mathias
A1  - de Giovannini, Umberto
A1  - Rubio, Angel
A1  - Ramsey, Michael G.
A1  - Bocquet, François C.
A1  - Soubatch, Serguei
A1  - Tautz, F. Stefan
A1  - Puschnig, Peter
A1  - Moser, Simon
T1  - Simple extension of the plane-wave final state in photoemission: bringing understanding to the photon-energy dependence of two-dimensional materials
T2  - Physical Review Research
N2  - Angle-resolved photoemission spectroscopy (ARPES) is a method that measures orbital and band structure contrast through the momentum distribution of photoelectrons. Its simplest interpretation is obtained in the plane-wave approximation, according to which photoelectrons propagate freely to the detector. The photoelectron momentum distribution is then essentially given by the Fourier transform of the real-space orbital. While the plane-wave approximation is remarkably successful in describing the momentum distributions of aromatic compounds, it generally fails to capture kinetic-energy-dependent final-state interference and dichroism effects. Focusing our present study on quasi-freestanding monolayer graphene as the archetypical two-dimensional (2D) material, we observe an exemplary E\(_{kin}\)-dependent modulation of, and a redistribution of spectral weight within, its characteristic horseshoe signature around the \(\bar {K}\) and \(\bar {K´}\) points: both effects indeed cannot be rationalized by the plane-wave final state. Our data are, however, in remarkable agreement with ab initio time-dependent density functional simulations of a freestanding graphene layer and can be explained by a simple extension of the plane-wave final state, permitting the two dipole-allowed partial waves emitted from the C 2p\(_z\) orbitals to scatter in the potential of their immediate surroundings. Exploiting the absolute photon flux calibration of the Metrology Light Source, this scattered-wave approximation allows us to extract E\(_{kin}\)-dependent amplitudes and phases of both partial waves directly from photoemission data. The scattered-wave approximation thus represents a powerful yet intuitive refinement of the plane-wave final state in photoemission of 2D materials and beyond.
Y1  - 2023
UR  - https://opus.bibliothek.uni-wuerzburg.de/frontdoor/index/index/docId/35033
UR  - https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-350330
VL  - 5
IS  - 3
ER  -