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Boné T, Windischbacher A, Scheucher L, Presel F, Schnabl P, Wagner MS, Bettinger HF, Peisert H, Chassé T, Puschnig P, Ramsey MG, Sterrer M, Koller G. Orientation, electronic decoupling and band dispersion of heptacene on modified and nanopatterned copper surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:475003. [PMID: 37586386 DOI: 10.1088/1361-648x/acf105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 08/16/2023] [Indexed: 08/18/2023]
Abstract
The adsorption of heptacene (7 A) on Cu(110) and Cu(110)-(2 × 1)-O was studied with scanning tunneling microscopy, photoemission orbital tomography and density functional calculations to reveal the influence of surface passivation on the molecular geometry and electronic states. We found that the charge transfer into the 7 A molecules on Cu(110) is completely suppressed for the oxygen-modified Cu surface. The molecules are aligned along the Cu-O rows and uncharged. They are tilted due to the geometry enforced by the substrate and the ability to maximize intermolecular π-π overlap, which leads to strong π-band dispersion. The HOMO-LUMO gap of these decoupled molecules is significantly larger than that reported on weakly interacting metal surfaces. Finally, the Cu-O stripe phase was used as a template for nanostructured molecular growth and to assess possible confinement effects.
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Affiliation(s)
- Thomas Boné
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Andreas Windischbacher
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Lukas Scheucher
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Francesco Presel
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Paul Schnabl
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Marie S Wagner
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
- Institute of Organic Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Holger F Bettinger
- Institute of Organic Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Heiko Peisert
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Thomas Chassé
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Peter Puschnig
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Michael G Ramsey
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Martin Sterrer
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Georg Koller
- Institute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria
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Shi MX, Tao ML, Sun K, Li Z, Yang DX, Wang JZ. Structural transition and interconversion between the 2D self-assembled structures of pentacene. Phys Chem Chem Phys 2022; 24:17744-17750. [PMID: 35843214 DOI: 10.1039/d2cp01750d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The 2D self-assemblies and structural transitions of pentacene on a Cd(0001) surface have been investigated with low temperature scanning tunneling microscopy (STM). With increasing coverage, pentacene molecules show a structural evolution from the initial disordered gas-like phase through the porous network phase to the herringbone phase, and finally to the brickwall phase at the full monolayer. In particular, orientational frustration and cooperative rotation of pentacene molecules take place in the herringbone phase. Furthermore, successive STM scanning leads to structural interconversions between the porous network phase, herringbone phase, and brickwall phase, indicating the metastability of the 2D assembled structures of pentacene on Cd(0001). These structural transitions and interconversion can be attributed to the interplay between the repulsive electrostatic forces resulting from the charge transfer from the substrate to pentacene and the attractive effects originating from dipole-dipole interactions and intermolecular van der Waals forces.
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Affiliation(s)
- Ming-Xia Shi
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, China.
| | - Min-Long Tao
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, China.
| | - Kai Sun
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, China.
| | - Zuo Li
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, China.
| | - Da-Xiao Yang
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, China.
| | - Jun-Zhong Wang
- School of Physical Science and Technology, Southwest University, Chongqing, 400715, China.
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3
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Thomas A, Leoni T, Siri O, Becker C, Unzog M, Kern C, Puschnig P, Zeppenfeld P. A one-dimensional high-order commensurate phase of tilted molecules. Phys Chem Chem Phys 2022; 24:9118-9122. [PMID: 35383807 PMCID: PMC9020326 DOI: 10.1039/d2cp00437b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report on the formation of a high-order commensurate (HOC) structure of 5,14-dihydro-5,7,12,14-tetraazapentacene (DHTAP) molecules on the highly corrugated Cu(110)–(2 × 1)O surface. Scanning tunnelling microscopy shows that the DHTAP molecules form a periodic uniaxial arrangement in which groups of seven molecules are distributed over exactly nine substrate lattice spacings along the [1̄10] direction. DFT-calculations reveal that this peculiar arrangement is associated with different tilting of the seven DHTAP molecules within the quasi one-dimensional HOC unit cell. The orientational degree of freedom thus adds a new parameter, which can efficiently stabilize complex molecular structures on corrugated surfaces. We report on the formation of a quasi-1D high-order commensurate (HOC) structure of dihydro-tetraazapentacene (DHTAP) molecules on a Cu(110)–(2 × 1)O surface and its stabilization through internal degrees of freedoms, namely the molecular tilt.![]()
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Affiliation(s)
- Anthony Thomas
- Aix Marseille University, CNRS, CINaM UMR 7325, Campus de Luminy, 13288 Marseille cedex 09, France.
| | - Thomas Leoni
- Aix Marseille University, CNRS, CINaM UMR 7325, Campus de Luminy, 13288 Marseille cedex 09, France.
| | - Olivier Siri
- Aix Marseille University, CNRS, CINaM UMR 7325, Campus de Luminy, 13288 Marseille cedex 09, France.
| | - Conrad Becker
- Aix Marseille University, CNRS, CINaM UMR 7325, Campus de Luminy, 13288 Marseille cedex 09, France.
| | - Martin Unzog
- Institute of Physics, University of Graz, NAWI-Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Christian Kern
- Institute of Physics, University of Graz, NAWI-Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Peter Puschnig
- Institute of Physics, University of Graz, NAWI-Graz, Universitätsplatz 5, 8010 Graz, Austria
| | - Peter Zeppenfeld
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Straße 69, A-4040 Linz, Austria
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Wagner T, Antczak G, Ghanbari E, Navarro-Quezada A, Györök M, Volokitina A, Marschner F, Zeppenfeld P. Standard deviation of microscopy images used as indicator for growth stages. Ultramicroscopy 2022; 233:113427. [PMID: 34990906 DOI: 10.1016/j.ultramic.2021.113427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/18/2021] [Accepted: 11/12/2021] [Indexed: 11/29/2022]
Abstract
Photoelectron emission microscopy (PEEM) and low energy electron microscopy (LEEM) can easily distinguish between organic molecules adsorbed in crystallites or in the wetting layers as well as the bare metal substrate due to their different electronic properties. Already before (and during) the condensation of such solid phases (2D islands or 3D crystallites), there is a dilute 2D gas phase. Such a 2D gas phase consists of molecules, which are highly mobile and diffuse across the surface. The individual molecules are too small to be resolved in PEEM/LEEM images. Here, we discuss, how image features below and above the resolution limit of a PEEM/LEEM affect the mean electron yield and its (normalized) standard deviation. We support our findings with two experimental examples: the deposition of cobalt phthalocyanine (CoPc) on Ag(100) and of perfluoro-pentacene on Ag(110). Our results demonstrate, how a spatial and temporal analysis of image series can be used to obtain information about molecular phases, which cannot be directly resolved in microscopy images.
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Affiliation(s)
- Thorsten Wagner
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria.
| | - Grażyna Antczak
- University of Wrocław, Institute of Experimental Physics, Pl. M. Borna 9, 50-204 Wrocław, Poland.
| | - Ebrahim Ghanbari
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria
| | - Andrea Navarro-Quezada
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria; Johannes Kepler University, Institute of Semiconductor and Solid State Physics, Quantum Materials Group, Altenberger Str. 69, 4040 Linz, Austria.
| | - Michael Györök
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria.
| | - Anna Volokitina
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria
| | - Felix Marschner
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria
| | - Peter Zeppenfeld
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria.
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Navarro-Quezada A, Ghanbari E, Wagner T, Zeppenfeld P. Molecular Reorientation during the Initial Growth of Perfluoropentacene on Ag(110). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2018; 122:12704-12711. [PMID: 29963216 PMCID: PMC6018566 DOI: 10.1021/acs.jpcc.8b00869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 05/28/2018] [Indexed: 05/09/2023]
Abstract
Perfluoropentacene (PFP) is an organic material that has been widely studied over the last years and has already found applications in organic electronics. However, fundamental physical questions, such as the structural formation and the preferential orientation of the molecules during deposition on metal surfaces, are still not fully understood. In this work, we report on a unique in-plane molecular reorientation during the completion of the first monolayer of PFP on the Ag(110) surface. To characterize the molecular alignment, we have monitored the deposition process in real time using polarization-dependent differential reflectance spectroscopy and reflectance anisotropy spectroscopy. Abrupt changes in the optical signals reveal an intricate sequence of reorientation transitions of the PFP molecules upon monolayer completion and during the formation of the second monolayer, eventually leading to a full alignment of the long molecular axis along the [001] direction of the substrate and an enhanced structural ordering. Scanning tunneling microscopy and low-energy electron diffraction confirm the observed molecular reorientation upon monolayer compression and provide further details on the structural and orientational ordering of the PFP monolayer before and after compression.
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Affiliation(s)
- Andrea Navarro-Quezada
- Institute of Experimental Physics and Institute of Semiconductor and
Solid State Physics, Johannes Kepler University, Altenberger Street 69, 4040 Linz, Austria
- E-mail: (A.N.-Q)
| | - Ebrahim Ghanbari
- Institute of Experimental Physics and Institute of Semiconductor and
Solid State Physics, Johannes Kepler University, Altenberger Street 69, 4040 Linz, Austria
| | - Thorsten Wagner
- Institute of Experimental Physics and Institute of Semiconductor and
Solid State Physics, Johannes Kepler University, Altenberger Street 69, 4040 Linz, Austria
- E-mail: (T.W.)
| | - Peter Zeppenfeld
- Institute of Experimental Physics and Institute of Semiconductor and
Solid State Physics, Johannes Kepler University, Altenberger Street 69, 4040 Linz, Austria
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Shen W, Hu C, Tao J, Liu J, Fan S, Wei Y, An C, Chen J, Wu S, Li Y, Liu J, Zhang D, Sun L, Hu X. Resolving the optical anisotropy of low-symmetry 2D materials. NANOSCALE 2018; 10:8329-8337. [PMID: 29687795 DOI: 10.1039/c7nr09173g] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Optical anisotropy is one of the most fundamental physical characteristics of emerging low-symmetry two-dimensional (2D) materials. It provides abundant structural information and is crucial for creating diverse nanoscale devices. Here, we have proposed an azimuth-resolved microscopic approach to directly resolve the normalized optical difference along two orthogonal directions at normal incidence. The differential principle ensures that the approach is only sensitive to anisotropic samples and immune to isotropic materials. We studied the optical anisotropy of bare and encapsulated black phosphorus (BP) and unveiled the interference effect on optical anisotropy, which is critical for practical applications in optical and optoelectronic devices. A multi-phase model based on the scattering matrix method was developed to account for the interference effect and then the crystallographic directions were unambiguously determined. Our result also suggests that the optical anisotropy is a probe to measure the thickness with monolayer resolution. Furthermore, the optical anisotropy of rhenium disulfide (ReS2), another class of anisotropic 2D materials, with a 1T distorted crystal structure, was investigated, which demonstrates that our approach is suitable for other anisotropic 2D materials. This technique is ideal for optical anisotropy characterization and will inspire future efforts in BP and related anisotropic 2D nanomaterials for engineering new conceptual nanodevices.
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Affiliation(s)
- Wanfu Shen
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, No. 92 Weijin Road, CN-300072 Tianjin, China.
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Navarro-Quezada A, Aiglinger M, Ghanbari E, Wagner T, Zeppenfeld P. Polarization-dependent differential reflectance spectroscopy for real-time monitoring of organic thin film growth. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:113108. [PMID: 26628122 DOI: 10.1063/1.4936352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
By monitoring the reflectance of a sample surface during deposition of a thin organic film, one can obtain information with submonolayer resolution in real-time. A special kind of optical spectroscopy is Differential Reflectance Spectroscopy (DRS), which compares the reflectance before and during deposition of a thin film or any other change of the surface optical properties. In this work, we present an extended DRS setup that allows monitoring simultaneously both linear polarization states (s and p) of the reflected light. We implement polarization-dependent DRS to monitor the growth of perflouropentacene thin films on a Ag(110) single crystal. The setup allows us to deduce the optical anisotropy of the sample and, in particular, the preferred orientation of the molecules on the surface.
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Affiliation(s)
- A Navarro-Quezada
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| | - M Aiglinger
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| | - E Ghanbari
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| | - Th Wagner
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| | - P Zeppenfeld
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
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