Angle resolved photoemission from organic semiconductors: orbital imaging beyond the molecular orbital interpretation
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- Fascinating pictures that can be interpreted as showing molecular orbitals have been obtained with various imaging techniques. Among these, angle resolved photoemission spectroscopy (ARPES) has emerged as a particularly powerful method. Orbital images have been used to underline the physical credibility of the molecular orbital concept. However, from the theory of the photoemission process it is evident that imaging experiments do not show molecular orbitals, but Dyson orbitals. The latter are not eigenstates of a single-particle HamiltonianFascinating pictures that can be interpreted as showing molecular orbitals have been obtained with various imaging techniques. Among these, angle resolved photoemission spectroscopy (ARPES) has emerged as a particularly powerful method. Orbital images have been used to underline the physical credibility of the molecular orbital concept. However, from the theory of the photoemission process it is evident that imaging experiments do not show molecular orbitals, but Dyson orbitals. The latter are not eigenstates of a single-particle Hamiltonian and thus do not fit into the usual simple interpretation of electronic structure in terms of molecular orbitals. In a combined theoretical and experimental study we thus check whether a Dyson-orbital and a molecular-orbital based interpretation of ARPES lead to differences that are relevant on the experimentally observable scale. We discuss a scheme that allows for approximately calculating Dyson orbitals with moderate computational effort. Electronic relaxation is taken into account explicitly. The comparison reveals that while molecular orbitals are frequently good approximations to Dyson orbitals, a detailed understanding of photoemission intensities may require one to go beyond the molecular orbital picture. In particular we clearly observe signatures of the Dyson-orbital character for an adsorbed semiconductor molecule in ARPES spectra when these are recorded over a larger momentum range than in earlier experiments.…
Autor(en): | M. Dauth, M. Wiessner, V. Feyer, A. Schöll, P. Puschnig, F. Reinert, S. Kuemmel |
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URN: | urn:nbn:de:bvb:20-opus-115180 |
Dokumentart: | Artikel / Aufsatz in einer Zeitschrift |
Institute der Universität: | Fakultät für Physik und Astronomie / Physikalisches Institut |
Sprache der Veröffentlichung: | Englisch |
Titel des übergeordneten Werkes / der Zeitschrift (Englisch): | New Journal of Physics |
ISSN: | 1367-2630 |
Erscheinungsjahr: | 2014 |
Band / Jahrgang: | 16 |
Seitenangabe: | 103005 |
Originalveröffentlichung / Quelle: | New Journal of Physics 16 (2014) 103005. DOI: 10.1088/1367-2630/16/10/103005 |
DOI: | https://doi.org/10.1088/1367-2630/16/10/103005 |
Allgemeine fachliche Zuordnung (DDC-Klassifikation): | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
Freie Schlagwort(e): | AG(110); ARPES; Dyson orbitals; NTCDA; PTCDA; approximation; density-functional theory; electronic structure; energies; monolayers; orbital imaging; photoemission spectroscopy; spectroscopy |
Datum der Freischaltung: | 11.07.2015 |
Lizenz (Deutsch): | CC BY: Creative-Commons-Lizenz: Namensnennung |