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Binding and Electronic Level Alignment of $\boldsymbolπ$-Conjugated Systems on Metals
Authors:
Antoni Franco-Cañellas,
Steffen Duhm,
Alexander Gerlach,
Frank Schreiber
Abstract:
We review the binding and energy level alignment of $π$-conjugated systems on metals, a field which during the last two decades has seen tremendous progress both in terms of experimental characterization as well as in the depth of theoretical understanding. Precise measurements of vertical adsorption distances and the electronic structure together with \textit{ab-initio} calculations have shown th…
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We review the binding and energy level alignment of $π$-conjugated systems on metals, a field which during the last two decades has seen tremendous progress both in terms of experimental characterization as well as in the depth of theoretical understanding. Precise measurements of vertical adsorption distances and the electronic structure together with \textit{ab-initio} calculations have shown that most of the molecular systems have to be considered as intermediate cases between weak physisorption and strong chemisorption. In this regime, the subtle interplay of different effects such as covalent bonding, charge transfer, electrostatic and van der Waals interactions yields a complex situation with different adsorption mechanisms. In order to establish a better understanding of the binding and the electronic level alignment of $π$-conjugated molecules on metals, we provide an up-to-date overview of the literature, explain the fundamental concepts as well as the experimental techniques and discuss typical case studies. Thereby, we relate the geometric with the electronic structure in a consistent picture and over the entire range from weak to strong coupling.
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Submitted 29 April, 2020; v1 submitted 22 February, 2020;
originally announced February 2020.
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Exploring the Bonding of Large Hydrocarbons on Noble Metals: Diindoperylene on Cu(111), Ag(111), and Au(111)
Authors:
C. Bürker,
N. Ferri,
A. Tkatchenko,
A. Gerlach,
J. Niederhausen,
T. Hosokai,
S. Duhm,
J. Zegenhagen,
N. Koch,
F. Schreiber
Abstract:
We present a benchmark study for the adsorption of a large pi-conjugated organic molecule on different noble metal surfaces, which is based on X-ray standing wave (XSW) measurements and density functional theory calculations with van der Waals (vdW) interactions. The bonding distances of diindenoperylene on Cu(111), Ag(111), and Au(111) surfaces (2.51 A, 3.01 A, and 3.10 A, respectively) determine…
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We present a benchmark study for the adsorption of a large pi-conjugated organic molecule on different noble metal surfaces, which is based on X-ray standing wave (XSW) measurements and density functional theory calculations with van der Waals (vdW) interactions. The bonding distances of diindenoperylene on Cu(111), Ag(111), and Au(111) surfaces (2.51 A, 3.01 A, and 3.10 A, respectively) determined with the normal incidence XSW technique are compared with calculations. Excellent agreement with the experimental data, i.e. deviations less than 0.1 A, is achieved using the Perdew-Burke-Ernzerhof functional with vdW interactions that include the collective response of substrate electrons (PBE+vdW^{surf} method). Noteworthy, the calculations show that the vdW contribution to the adsorption energy increases in the order Au(111) < Ag(111) < Cu(111).
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Submitted 25 April, 2013; v1 submitted 12 April, 2013;
originally announced April 2013.
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Accessing surface Brillouin zone and band structure of picene single crystals
Authors:
Qian Xin,
Steffen Duhm,
Fabio Bussolotti,
Kouki Akaike,
Yoshihiro Kubozono,
Hideo Aoki,
Taichi Kosugi,
Satoshi Kera,
Nobuo Ueno
Abstract:
We have experimentally revealed the band structure and the surface Brillouin zone of insulating picene single crystals (SCs), the mother organic system for a recently discovered aromatic superconductor, with ultraviolet photoelectron spectroscopy (UPS) and low-energy electron diffraction with laser for photoconduction. A hole effective mass of 2.24 m_0 and the hole mobility mu_h >= 9.0 cm^2/Vs (29…
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We have experimentally revealed the band structure and the surface Brillouin zone of insulating picene single crystals (SCs), the mother organic system for a recently discovered aromatic superconductor, with ultraviolet photoelectron spectroscopy (UPS) and low-energy electron diffraction with laser for photoconduction. A hole effective mass of 2.24 m_0 and the hole mobility mu_h >= 9.0 cm^2/Vs (298 K) were deduced in Gamma-Y direction. We have further shown that some picene SCs did not show charging during UPS even without the laser, which indicates that pristine UPS works for high-quality organic SCs.
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Submitted 9 October, 2012; v1 submitted 18 April, 2012;
originally announced April 2012.
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Orientational Ordering of Nonplanar Phthalocyanines on Cu(111): Strength and Orientation of the Electric Dipole Moment
Authors:
A. Gerlach,
T. Hosokai,
S. Duhm,
S. Kera,
O. T. Hofmann,
E. Zojer,
J. Zegenhagen,
F. Schreiber
Abstract:
In order to investigate the orientational ordering of molecular dipoles and the associated electronic properties, we studied the adsorption of chlorogallium phthalocyanine molecules (GaClPc, Pc=C_32N_8H_16) on Cu(111) using the X-ray standing wave technique, photoelectron spectroscopy, and quantum chemical calculations. We find that for sub-monolayer coverages on Cu(111) the majority of GaClPc mol…
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In order to investigate the orientational ordering of molecular dipoles and the associated electronic properties, we studied the adsorption of chlorogallium phthalocyanine molecules (GaClPc, Pc=C_32N_8H_16) on Cu(111) using the X-ray standing wave technique, photoelectron spectroscopy, and quantum chemical calculations. We find that for sub-monolayer coverages on Cu(111) the majority of GaClPc molecules adsorb in a 'Cl-down' configuration by forming a covalent bond to the substrate. For bilayer coverages the XSW data indicate a co-existence of the 'Cl-down' and 'Cl-up' configuration on the substrate. The structural details established for both cases and supplementary calculations of the adsorbate system allow us to analyze the observed change of the work function.
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Submitted 11 April, 2011;
originally announced April 2011.