We study the molecular structure of one monolayer of picene on a Ag(100) surface. Low energy electron diffraction and scanning tunneling microscopy experiments show that the molecules arrange in a highly ordered manner exhibiting a point-on-line epitaxy with two differently arranged molecules per unit cell. Comparing measured and simulated photoelectron momentum maps allows further conclusions about the composition of the unit cell. The structural basis consists of two parallel molecules; one molecule lies face-on and the other is tilted by ≈45° around its long axis with respect to the surface normal.
Herein,
we have studied highly ordered two-dimensional layers of
1,2:8,9-dibenzopentacene (trans-DBPen) adsorbed on
a single-crystalline silver surface. While its parent molecule pentacene
is known for a relatively high hole mobility, reports on trans-DBPen are rather scarce. Furthermore, it belongs to polycyclic aromatic
hydrocarbons for which superconducting properties have been observed
upon intercalation with potassium. Our scanning tunneling microscopy
and low-energy electron diffraction results reveal a highly ordered
monolayer structure of trans-DBPen on Ag(111). We
further used angle-resolved ultraviolet photoelectron spectroscopy
to measure photoelectron momentum maps (PMMs). The experimental PMMs
agree very nicely with simulations based on our structural data while
assuming free molecules for the density functional theory calculations.
A comparison with pentacene yields some insights into the properties
of the two related molecules. We conclude that the degree of hybridization
between the molecular orbitals and substrate states is comparatively
weak. These results are expected to serve as a starting point for
future investigations of K-doped monolayers of trans-DBPen.
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.
Metrics & MoreArticle RecommendationsI n our contribution we discussed different properties of the organic molecule 1,2:8,9-dibenzopentacene (trans-DBPen) in the monolayer (ML) regime on Ag(111). Unfortunately, we made a mistake in a coordinate transformation regarding the result of the photoelectron momentum map (PMM) simulations. Consequently, the structural model in Figure 3d of the original paper, 1 reproduced in Figure 1a here, has to be replaced by the one in Figure 1b.
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