Electronic structure of 1ML NTCDA/Ag(111) studied by photoemission spectroscopy

Bendounan, Azzedine; Förster, Frank; Schöll, A.; Batchelor, David; Ziroff, J.; Umbach, E.; Reinert, F.

doi:10.1016/j.susc.2007.04.054

Cited by 51 publications

(62 citation statements)

References 32 publications

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“…The ARPES data for NTCDA/Ag(110) was recorded at beamline 9 Å of the Hiroshima Synchrotron Radiation Centre using photons with circular polarization and a photon energy hv ¼ 36 eV. The beamline is equipped with a 6-axes manipulator (i-GONIO, R-Dec Co.) and a Scienta R4000 photoelectron analyser enabling photoemission measurements with an energy resolution better than 10 meV at a base pressure of 4 Â 10 À 11 mbar 35,38,44,45 .…”

Section: Methodsmentioning

confidence: 99%

Substrate-mediated band-dispersion of adsorbate molecular states

et al. 2013

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Charge carrier mobilities in molecular condensates are usually small, as the coherent transport, which is highly effective in conventional semiconductors, is impeded by disorder and the small intermolecular coupling. A significant band dispersion can usually only be observed in exceptional cases such as for p-stacking of aromatic molecules in organic single crystals. Here based on angular resolved photoemission, we demonstrate on the example of planar p-conjugated molecules that the hybridization with a metal substrate can substantially increase the delocalization of the molecular states in selective directions along the surface. Supported by ab initio calculations we show how this mechanism couples the individual molecules within the organic layer resulting in an enhancement of the in-plane charge carrier mobility.

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Section: Methodsmentioning

confidence: 99%

Substrate-mediated band-dispersion of adsorbate molecular states

et al. 2013

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“…Similar to PTCDA on Ag(111), it also features a LUMO peak at E F , as evidenced in UPS measurements. [140][141][142] We relax the NTCDA-Ag(111) geometry with the PBE + vdW surf method 122 as implemented in VASP, using 3 layers of Ag(111) and a 4 × 4 surface unit cell as the substrate. The level alignment calculations are carried out using a 4 × 4 × 1 k-mesh (2 × 2 × 1 for the Fock exchange contribution).…”

Section: Ntcda On Ag(111)mentioning

confidence: 99%

Energy level alignment at molecule-metal interfaces from an optimally tuned range-separated hybrid functional

Liu

Egger

Refaely-Abramson

et al. 2017

The Journal of Chemical Physics

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The alignment of the frontier orbital energies of an adsorbed molecule with the substrate Fermi level at metal-organic interfaces is a fundamental observable of significant practical importance in nanoscience and beyond. Typical density functional theory calculations, especially those using local and semi-local functionals, often underestimate level alignment leading to inaccurate electronic structure and charge transport properties. In this work, we develop a new fully self-consistent predictive scheme to accurately compute level alignment at certain classes of complex heterogeneous molecule-metal interfaces based on optimally tuned range-separated hybrid functionals. Starting from a highly accurate description of the gas-phase electronic structure, our method by construction captures important nonlocal surface polarization effects via tuning of the long-range screened exchange in a range-separated hybrid in a non-empirical and system-specific manner. We implement this functional in a plane-wave code and apply it to several physisorbed and chemisorbed molecule-metal interface systems. Our results are in quantitative agreement with experiments, for both the level alignment and work function changes. Our approach constitutes a new practical scheme for accurate and efficient calculations of the electronic structure of molecule-metal interfaces.

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“…These states appear above the "background" of the metal substrate states, and show a characteristic angle dependence of the photoemission intensities [28] (see supplement), whereas an energy dispersion in dependence on k can not be observed [29]. As in the related system PTCDA/Ag(111) [9,28,30] the LUMO, unoccupied in case of the isolated molecule, is cut by the Fermi edge, demonstrating a partial occupation of this state by a transfer of electrons from the substrate to the molecule.…”

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confidence: 99%

Low-energy scale excitations in the spectral function of organic monolayer systems

et al. 2012

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Using high-resolution photoemission spectroscopy we demonstrate that the electronic structure of several organic monolayer systems, in particular 1,4,5,8-naphthalene tetracarboxylic dianhydride and Copper-phtalocyanine on Ag(111), is characterized by a peculiar excitation feature right at the Fermi level. This feature displays a strong temperature dependence and is immediatly connected to the binding energy of the molecular states, determined by the coupling between the molecule and the substrate. At low temperatures, the line-width of this feature, appearing on top of the partly occupied lowest unoccupied molecular orbital of the free molecule, amounts to only ≈ 25 meV, representing an unusually small energy scale for electronic excitations in these systems. We discuss possible origins, related e.g. to many-body excitations in the organic-metal adsorbate system, in particular a generalized Kondo scenario based on the single impurity Anderson model. For more than twenty years there has been a thorough investigation on π-conjugated organic molecules, which have shown to be suitable for the application in organic electronic devices [1][2][3]. These molecules often form long-range ordered films on single-crystalline metal substrates, allowing a systematic and fundamental study by various surface sensitive techniques. In particular from electron spectroscopy methods, as photoemission spectroscopy (PES), inverse photoemission (IPES), and x-ray absorption (XAS), deep insight into many important features of the electronic properties of condensed films and their interfaces has been achieved [4][5][6][7][8]. The latter are of particular importance since they crucially determine the properties of possible devices. Additional microscopic and spectroscopic information has been obtained by use of scanning tunneling microscopy (STM), leading to complementary information about the relation between geometrical and electronic structure [9][10][11][12].Usually, even the spectra of highly ordered films show features with a line-width of several hundreds of meV, mostly determined by vibronic excitations within the adsorbed molecule [7,13,14]. Therefore, even experiments with modern high-resolution photoemission spectrometers for VUV photoemission (UPS) display only features which are about two orders of magnitude larger than the most narrow peaks in other solid state or surface systems [15]. Local spectroscopic measurements by STM, on the other hand, show narrow features in the tunneling conductivity measurements through a single molecule [10,[16][17][18][19], which have been attributed to a possible Kondo like process within the charge transport through * present address: SOLEIL L'Orme des Merisiers, Saint-Aubin -BP 48, 91192 GIF-sur-YVETTE CEDEX FRANCE SOLEIL, Paris, France the adsorbed molecule. However, neither a direct evidence of a local magnetic moment, necessary for the Kondo effect, nor an immediate experimental observation of the spectral function does exist yet.Here we report about a high-resolution photoemission study o...

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Electronic structure of 1ML NTCDA/Ag(111) studied by photoemission spectroscopy

Cited by 51 publications

References 32 publications

Substrate-mediated band-dispersion of adsorbate molecular states

Substrate-mediated band-dispersion of adsorbate molecular states

Energy level alignment at molecule-metal interfaces from an optimally tuned range-separated hybrid functional

Low-energy scale excitations in the spectral function of organic monolayer systems

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