Growth of coronene on (100)- and (111)-surfaces of fcc-crystals

Huempfner, Tobias; Helgert, Christian; Forker, Roman; Fritz, Torsten

doi:10.1016/j.susc.2015.04.019

Cited by 20 publications

(31 citation statements)

References 28 publications

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“…Given the fact that high resolution data in combination with a spot finding algorithm and lattice fitting in distortion-corrected LEED patterns were all required to safely identify the incommensurability of HBC on graphite and to determine the epitaxial relation with sufficient accuracy for a numerical model, we suppose that incommensurate orientational epitaxy driven by SDWs might be far more common than has been assumed so far. Indeed, there are quite a few not fully understood epitaxial but incommensurate organic adlayer systems 17 , 19 which might be caused by similar local relaxations and may likewise be explainable by our approach. The only requirement for the prediction of the epitaxial orientation is a realistic model for the contributing energies to calculate the corresponding gradients.…”

Section: Discussionmentioning

confidence: 82%

Flexible 2D Crystals of Polycyclic Aromatics Stabilized by Static Distortion Waves

et al. 2016

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The epitaxy of many organic films on inorganic substrates can be classified within the framework of rigid lattices which helps to understand the origin of energy gain driving the epitaxy of the films. Yet, there are adsorbate–substrate combinations with distinct mutual orientations for which this classification fails and epitaxy cannot be explained within a rigid lattice concept. It has been proposed that tiny shifts in atomic positions away from ideal lattice points, so-called static distortion waves (SDWs), are responsible for the observed orientational epitaxy in such cases. Using low-energy electron diffraction and scanning tunneling microscopy, we provide direct experimental evidence for SDWs in organic adsorbate films, namely hexa-peri-hexabenzocoronene on graphite. They manifest as wave-like sub-Ångström molecular displacements away from an ideal adsorbate lattice which is incommensurate with graphite. By means of a density-functional-theory based model, we show that, due to the flexibility in the adsorbate layer, molecule–substrate energy is gained by straining the intermolecular bonds and that the resulting total energy is minimal for the observed domain orientation, constituting the orientational epitaxy. While structural relaxation at an interface is a common assumption, the combination of the precise determination of the incommensurate epitaxial relation, the direct observation of SDWs in real space, and their identification as the sole source of epitaxial energy gain constitutes a comprehensive proof of this effect.

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Section: Discussionmentioning

confidence: 82%

Flexible 2D Crystals of Polycyclic Aromatics Stabilized by Static Distortion Waves

et al. 2016

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“…The small deviation to the experimental value (∼7°) could be due to the Au(111) surface reconstruction, 32 which was not considered in the DFT calculations. Because the unit-cell dimensions are identical on the Au(111) and the Ag(111) surface, 11 , 31 a similar film geometry is expected in both cases, although a Ag(111) surface reconstruction is not present. In the case of Ag(111), the calculation of the total energy shows that the energetically favored configuration adopts a rotational angle of 6°, which is, as expected, close to the rotational angle on Au(111).…”

Section: Resultsmentioning

confidence: 94%

“…Previous STM and low-energy electron diffraction (LEED) measurements on coronene films on Ag(111) revealed that submonolayer films are poorly ordered up to a coverage of 0.9 ML. 11 The molecules adopt a noncommensurate film structure for increasing coverage, which continuously changes to a 4 × 4 commensurate superstructure at the coverage of 1 ML. In the case of coronene monolayers on Au(111), the films adopt a 4 × 4 geometry as well, as shown in ref ( 31 ) by means of LEED and STM.…”

Section: Resultsmentioning

confidence: 99%

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Influence of Film and Substrate Structure on Photoelectron Momentum Maps of Coronene Thin Films on Ag(111)

et al. 2017

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Angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) was measured for one-monolayer coronene films deposited on Ag(111). The (kx,ky)-dependent photoelectron momentum maps (PMMs), which were extracted from the ARUPS data by cuts at fixed binding energies, show finely structured patterns for the highest and the second-highest occupied molecular orbitals. While the substructure of the PMM main features is related to the 4 × 4 commensurate film structure, various features with three-fold symmetry imply an additional influence of the substrate. PMM simulations on the basis of both free-standing coronene assemblies and coronene monolayers on the Ag(111) substrate confirm a sizable molecule–molecule interaction because no substructure was observed for PMM simulations using free coronene molecules.

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“…Making use of the tremendous variability of the molecular building blocks, the intermolecular and the molecule-surface interactions can be controlled to arrive at a specific surface structure that is encoded in the involved constituents [7,8]. In many cases, the molecule-substrate interaction has been recognized to be governed by the electronic structure of the substrate, which, in turn, impacts the structural properties of self-assembled nanomaterials on various substrates; e.g., bulk metals [9][10][11][12][13][14][15], twodimensional materials [16,17], and polar oxide surfaces [18][19][20]. Tuning the subtle balance between molecule-molecule and molecule-surface interactions [21] has opened up new pathways for creating an impressive variety of molecular structures on surfaces [22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Tailoring molecular island shapes: influence of microscopic interaction on mesostructure

et al. 2020

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Controlling the structure formation of molecules on surfaces is fundamental for creating molecular nanostructures with tailored properties and functionalities and relies on tuning the subtle balance between intermolecular and molecule-surface interactions. So far, however, reliable rules of design are largely lacking, preventing the controlled fabrication of self-assembled functional structures on surfaces. In addition, while so far many studies focused on varying the molecular building blocks, the impact of systematically adjusting the underlying substrate has been less frequently addressed. Here, we elucidate the potential of tailoring the mesoscopic island shape by tuning the interactions at the molecular level. As a model system, we have selected the molecule dimolybdenum tetraacetate on three prototypical surfaces, Cu(111), Au(111) and CaF 2 (111). While providing the same hexagonal geometry, compared to Cu(111), the lattice constants of Au(111) and CaF 2 (111) differ by a factor of 1.1 and 1.5, respectively. Our high-resolution scanning probe microscopy images reveal molecular-level information on the resulting islands and elucidate the molecular-level design principles for the observed mesoscopic island shapes. Our study demonstrates the capability to tailor the mesoscopic island shape by exclusively tuning the substrate lattice constant, in spite of the very different electronic structure of the substrates involved. This work provides insights for developing general design strategies for controlling molecular mesostructures on surfaces.

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Growth of coronene on (100)- and (111)-surfaces of fcc-crystals

Cited by 20 publications

References 28 publications

Flexible 2D Crystals of Polycyclic Aromatics Stabilized by Static Distortion Waves

Flexible 2D Crystals of Polycyclic Aromatics Stabilized by Static Distortion Waves

Influence of Film and Substrate Structure on Photoelectron Momentum Maps of Coronene Thin Films on Ag(111)

Tailoring molecular island shapes: influence of microscopic interaction on mesostructure

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