Well-ordered monolayers of alkali-doped coronene and picene: Molecular arrangements and electronic structures

Abstract

Adsorptions of alkali metals (such as K and Li) on monolayers of coronene and picene realize the formation of ordered phases, which serve as well-defined model systems for metal-intercalated aromatic superconductors. Upon alkali-doping of the monolayers of coronene and picene, scanning tunneling microscopy and X-ray absorption spectroscopy revealed the rearrangement of the entire molecular layer. The K-induced reconstruction of both monolayers resulted in the formation of a structure with a herringbone-like arrangement of molecules, suggesting the intercalation of alkali metals between molecular planes. Upon reconstruction, a shift in both the vacuum level and core levels of coronene was observed as a result of a charge transfer from alkali metals to coronene. In addition, a new density of states near the Fermi level was formed in both the doped coronene and the doped picene monolayers. This characteristic electronic feature of the ordered monolayer has been also reported in the multilayer picene films, ensuring that the present monolayer can model the properties of the metal-intercalated aromatic hydrocarbons. It is suggested that the electronic structure near the Fermi level is sensitive to the molecular arrangement, and that both the strict control and determinations of the molecular structure in the doped phase should be important for the determination of the electronic structure of these materials.

Self-Assembly of Covalently Linked Porphyrin Dimers at the Solid–Liquid Interface

“…Similar as was observed in the other STM images of the porphyrin dimers, we propose that the bright lamellae correspond to the aromatic parts of MnCu2 and the darker regions to the alkyl chains. Similar ‘edge-on’ orientation geometries at the solid–liquid interface have previously been observed for porphyrin oligomers containing six [17] and twelve porphyrin moieties [18,19], phthalocyanine derivatives [48], and other planar molecules with extended aromatic surfaces [49,50,51,52,53]. The formation of the ‘edge-on’ assemblies of MnCu2 is most likely governed by stabilizing π-stacking between the aromatic porphyrin planes of the dimers.…”

Observation of gapped phases in potassium-doped single-layer p -terphenyl on Au (111)

“…1(c). We note that similar structures were also reported for other surfaceadsorbed phenyl molecules [16][17][18][19][20][21]. The inter-stripe and inter-molecule distances (labeled as a and b in Fig.…”

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

“…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).…”