1
|
Wagner T, Györök M, Wolfmayr S, Gründlinger P, Monkowius U, Zeppenfeld P. Aurophilic Molecules on Surfaces. Part II. (NapNC)AuCl on Au(111). ACS OMEGA 2023; 8:38083-38091. [PMID: 37867682 PMCID: PMC10586446 DOI: 10.1021/acsomega.3c04152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/18/2023] [Indexed: 10/24/2023]
Abstract
Although aurophilicity is a well-known phenomenon in structural gold chemistry and is found in many crystals of Au(I) complexes, its potential for self-assembly in thin films is not yet explored. This paper is Part II of a study, in which we investigated the ultrathin film formation of chlorido(2-naphthyl isonitrile) gold(I) on gold surfaces. Here, we present the data for the growth of (NapNC)AuCl on isotropic Au(111) surfaces. Already during physical vapor deposition, the condensation of ultrathin films is monitored by photoelectron emission microscopy (PEEM) and incremental and spectrally resolved changes in the optical reflectance (DDRS). Additional structural data obtained by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) reveal that the "crossed swords" packing motif known from the bulk is also present in thin films.
Collapse
Affiliation(s)
- Thorsten Wagner
- Institute
of Experimental Physics, Surface Science Division, Johannes Kepler University, Altenberger Straße 69, 4040 Linz, Austria
| | - Michael Györök
- Institute
of Experimental Physics, Surface Science Division, Johannes Kepler University, Altenberger Straße 69, 4040 Linz, Austria
| | - Sebastian Wolfmayr
- Institute
of Experimental Physics, Surface Science Division, Johannes Kepler University, Altenberger Straße 69, 4040 Linz, Austria
| | - Petra Gründlinger
- Institute
of Experimental Physics, Surface Science Division, Johannes Kepler University, Altenberger Straße 69, 4040 Linz, Austria
| | - Uwe Monkowius
- School
of Education, Chemistry, Johannes Kepler
University, Altenberger
Straße 69, 4040 Linz, Austria
| | - Peter Zeppenfeld
- Institute
of Experimental Physics, Surface Science Division, Johannes Kepler University, Altenberger Straße 69, 4040 Linz, Austria
| |
Collapse
|
2
|
Wagner T, Antczak G, Györök M, Sabik A, Volokitina A, Gołek F, Zeppenfeld P. Attenuation of Photoelectron Emission by a Single Organic Layer. ACS APPLIED MATERIALS & INTERFACES 2022; 14:23983-23989. [PMID: 35537096 PMCID: PMC9136842 DOI: 10.1021/acsami.2c02996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/20/2022] [Indexed: 06/14/2023]
Abstract
We report an in situ study of the thin-film growth of cobalt-phthalocyanine on Ag(100) surfaces using photoelectron emission microscopy (PEEM) and the Anderson method. Based on the Fowler-DuBridge theory, we were able to correlate the evolution of the mean electron yield acquired with PEEM for coverages up to two molecular layers of cobalt-phthalocyanine to the global work function changes measured with the Anderson method. For coverages above two monolayers, the transients measured with the Anderson method and those obtained with PEEM show different trends. We exploit this discrepancy to determine the inelastic mean free path of the low-energy electrons while passing through the third layer of CoPc.
Collapse
Affiliation(s)
- Thorsten Wagner
- Johannes
Kepler University, Institute of Experimental Physics, Surface Science
Division, Altenberger Strasse 69, 4040 Linz, Austria
| | - Grażyna Antczak
- University
of Wroclaw, Institute of Experimental Physics, Pl. M. Borna 9, 50-204 Wroclaw, Poland
| | - Michael Györök
- Johannes
Kepler University, Institute of Experimental Physics, Surface Science
Division, Altenberger Strasse 69, 4040 Linz, Austria
| | - Agata Sabik
- University
of Wroclaw, Institute of Experimental Physics, Pl. M. Borna 9, 50-204 Wroclaw, Poland
| | - Anna Volokitina
- Johannes
Kepler University, Institute of Experimental Physics, Surface Science
Division, Altenberger Strasse 69, 4040 Linz, Austria
| | - Franciszek Gołek
- University
of Wroclaw, Institute of Experimental Physics, Pl. M. Borna 9, 50-204 Wroclaw, Poland
| | - Peter Zeppenfeld
- Johannes
Kepler University, Institute of Experimental Physics, Surface Science
Division, Altenberger Strasse 69, 4040 Linz, Austria
| |
Collapse
|
3
|
Kratzer M, Szajna K, Wrana D, Belza W, Krok F, Teichert C. Fabrication of ion bombardment induced rippled TiO 2 surfaces to influence subsequent organic thin film growth. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:283001. [PMID: 29790863 DOI: 10.1088/1361-648x/aac758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Control over organic thin film growth is a central issue in the development of organic electronics. The anisotropy and extended size of the molecular building blocks introduce a high degree of complexity within the formation of thin films. This complexity can be even increased for substrates with induced, sophisticated morphology and anisotropy. Thus, targeted structuring like ion beam mediated modification of substrates in order to create ripples, pyramids, or pit structures provides a further degree of freedom in manipulating the growth morphology of organic thin films. We provide a comprehensive review of recent work on para-hexaphenyl (C36H26, 6P) as a typical representative of the class of small, rod-like conjugated molecules and rutile TiO2(1 1 0) as an example for a transparent oxide electrode to demonstrate the effect of ion beam induced nanostructuring on organic thin film growth. Starting from molecular growth on smooth, atomically flat TiO2(1 1 0) (1 × 1) surfaces, we investigate the influence of the ripple size on the resulting 6P thin films. The achieved 6P morphologies are either crystalline nano-needles composed of flat lying molecules or islands consisting of upright standing 6P, which are elongated in ripple direction. The islands' length-to-width ratio can be controlled by tuning the ripples' shape.
Collapse
Affiliation(s)
- M Kratzer
- Montanuniversitaet Leoben, Franz Josef Straße 18, 8700 Leoben, Austria
| | | | | | | | | | | |
Collapse
|
4
|
Szajna K, Kratzer M, Wrana D, Mennucci C, Jany BR, Buatier de Mongeot F, Teichert C, Krok F. Influence of TiO2(110) surface roughness on growth and stability of thin organic films. J Chem Phys 2016; 145:144703. [DOI: 10.1063/1.4964370] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- K. Szajna
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Krakow 30-348, Poland
| | - M. Kratzer
- Institute of Physics, Montanuniversitat Leoben, Leoben 8700, Austria
| | - D. Wrana
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Krakow 30-348, Poland
| | - C. Mennucci
- Dipartimento di Fisica, Università di Genova, Genova 16146, Italy
| | - B. R. Jany
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Krakow 30-348, Poland
| | | | - C. Teichert
- Institute of Physics, Montanuniversitat Leoben, Leoben 8700, Austria
| | - F. Krok
- Marian Smoluchowski Institute of Physics, Jagiellonian University, Krakow 30-348, Poland
| |
Collapse
|
5
|
Kratzer M, Teichert C. Thin film growth of aromatic rod-like molecules on graphene. NANOTECHNOLOGY 2016; 27:292001. [PMID: 27299472 DOI: 10.1088/0957-4484/27/29/292001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Research on graphene (Gr) is a vastly expanding field due to its potential for technological applications. Its close structural and chemical relationship to conjugated organic molecules makes it a superior candidate as a transparent electrode material in organic electronics and optoelectronics. The growth of organic thin films-intensively investigated in the past few decades-has demonstrated the complexity in growth and nucleation processes arising from the anisotropy and spatial extension of the molecular building blocks. Choosing the small, conjugated rod-like molecules para-hexaphenyl and pentacene as model representatives for small organic molecules, we review recent findings in organic thin film growth on a variety of Gr substrates. Special attention is paid to the differences in the resulting growth arising from the various methods of Gr fabrication and support that affect both the Gr-molecule interfacing and the involved molecular diffusion processes.
Collapse
Affiliation(s)
- M Kratzer
- Institute of Physics, Montanuiversität Leoben, Franz Josef Straße 18, 8700 Leoben, Austria
| | | |
Collapse
|
6
|
Wagner M, Berkebile S, Netzer FP, Ramsey MG. Revealing the Buried Metal-Organic Interface: Restructuring of the First Layer by van der Waals Forces. ACS NANO 2015; 9:12070-12078. [PMID: 26505912 DOI: 10.1021/acsnano.5b05013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
With the use of molecular manipulation in a cryogenic scanning tunneling microscope, the structure and rearrangement of sexiphenyl molecules at the buried interface of the organic film with the Cu(110) substrate surface have been revealed. It is shown that a reconstruction of the first monolayer of flat lying molecules occurs due to the van der Waals pressure from subsequent layers. In this rearrangement, additional sexiphenyl molecules are forced into the established complete monolayer and adopt an edge-on configuration. Incorporation of second layer molecules into the first layer is also demonstrated by purposely pushing sexiphenyl molecules with the STM tip. The results indicate that even chemisorbed organic layers at interfaces can be significantly influenced by external stress from van der Waals forces of subsequent layers.
Collapse
Affiliation(s)
- Margareta Wagner
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University , 8010 Graz, Austria
| | - Stephen Berkebile
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University , 8010 Graz, Austria
| | - Falko P Netzer
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University , 8010 Graz, Austria
| | - Michael G Ramsey
- Surface and Interface Physics, Institute of Physics, Karl-Franzens University , 8010 Graz, Austria
| |
Collapse
|
7
|
Ghanbari E, Wagner T, Zeppenfeld P. Layer-Resolved Evolution of Organic Thin Films Monitored by Photoelectron Emission Microscopy and Optical Reflectance Spectroscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2015; 119:24174-24181. [PMID: 26523159 PMCID: PMC4620530 DOI: 10.1021/acs.jpcc.5b08083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 09/29/2015] [Indexed: 05/13/2023]
Abstract
Photoelectron emission microscopy (PEEM) and differential (optical) reflectance spectroscopy (DRS) have proven independently to be versatile analytical tools for monitoring the evolution of organic thin films during growth. In this paper, we present the first experiment in which both techniques have been applied simultaneously and synchronously. We illustrate how the combined PEEM and DRS results can be correlated to obtain an extended perspective on the electronic and optical properties of a molecular film dependent on the film thickness and morphology. As an example, we studied the deposition of the organic molecule α-sexithiophene on Ag(111) in the thickness range from submonolayers up to several monolayers.
Collapse
Affiliation(s)
- Ebrahim Ghanbari
- Institute of Experimental Physics, Johannes Kepler University , Altenberger Str. 69, 4040 Linz, Austria
| | - Thorsten Wagner
- Institute of Experimental Physics, Johannes Kepler University , Altenberger Str. 69, 4040 Linz, Austria
| | - Peter Zeppenfeld
- Institute of Experimental Physics, Johannes Kepler University , Altenberger Str. 69, 4040 Linz, Austria
| |
Collapse
|
8
|
Wagner T, Ghanbari E, Huber D, Zeppenfeld P. The growth of α-sexithiophene films on Ag(111) studied by means of PEEM with linearly polarized light. Ultramicroscopy 2015; 159 Pt 3:464-9. [PMID: 26150140 DOI: 10.1016/j.ultramic.2015.06.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 05/17/2015] [Accepted: 06/19/2015] [Indexed: 10/23/2022]
Abstract
In this study, we used photo electron emission microscopy (PEEM) to investigate the growth of α-sexithiophene (α-6 T) on Ag(111) surfaces. The experiments were carried out with linearly polarized ultraviolet-light (Hg lamp with hν=4.9 eV) in order to probe the alignment of the molecules on the surface. In particular, we acquired images before, during, and after growth while changing the polarization in a stepwise manner. For the stationary states of the clean and the α-6 T covered surfaces, we monitored the local electron yield and the intensity of the ultraviolet C-light (100-280 nm) reflected from the whole sample using PEEM and a photodiode, respectively. Due to the high ionization potential (IP>5 eV), there is no direct photoelectron emission from the organic crystallites. However, the photoelectron emission of the metal/organic interface is influenced by anisotropic absorption of the incident light beam, since the adsorbed molecules act as dichroic filters with distinct orientations.
Collapse
Affiliation(s)
- Thorsten Wagner
- Institute of Experimental Physics at the Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria.
| | - Ebrahim Ghanbari
- Institute of Experimental Physics at the Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria.
| | - Daniel Huber
- Institute of Experimental Physics at the Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria
| | - Peter Zeppenfeld
- Institute of Experimental Physics at the Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz, Austria.
| |
Collapse
|
9
|
Kratzer M, Wrana D, Szajna K, Krok F, Teichert C. Island shape anisotropy in organic thin film growth induced by ion-beam irradiated rippled surfaces. Phys Chem Chem Phys 2014; 16:26112-8. [DOI: 10.1039/c4cp03356f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
10
|
Wagner T, Györök M, Huber D, Zeppenfeld P, Głowacki ED. Quinacridone on Ag(111): Hydrogen Bonding versus Chirality. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2014; 118:10911-10920. [PMID: 24883168 PMCID: PMC4032182 DOI: 10.1021/jp502148x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 04/29/2014] [Indexed: 05/18/2023]
Abstract
Quinacridone (QA) has recently gained attention as an organic semiconductor with unexpectedly high performance in organic devices. The strong intermolecular connection via hydrogen bonds is expected to promote good structural order. When deposited on a substrate, another relevant factor comes into play, namely the 2D-chirality of the quinacridone molecules adsorbed on a surface. Scanning tunneling microscopy (STM) images of monolayer quinacridone on Ag(111) deposited at room temperature reveal the formation of quasi-one-dimensional rows of parallel quinacridone molecules. These rows are segmented into short stacks of a few molecules in which adjacent, flat-lying molecules of a single handedness are linked via hydrogen bonds. After annealing to a temperature of T = 550-570 K, which is close to the sublimation temperature of bulk quinacridone, the structure changes into a stacking of heterochiral quinacridone dimers with a markedly different intermolecular arrangement. Electron diffraction (LEED) and photoelectron emission microscopy (PEEM) data corroborate the STM findings. These results illustrate how the effects of hydrogen bonding and chirality can compete and give rise to very different (meta)stable structures of quinacridone on surfaces.
Collapse
Affiliation(s)
- Thorsten Wagner
- Institute
of Experimental Physics, Johannes Kepler
University Linz, Altenberger
Str. 69, 4040 Linz, Austria
- E-mail ; Ph +43 (0)732 2468 8505; Fax +43 (0)732 2468
8509 (T.W.)
| | - Michael Györök
- Institute
of Experimental Physics, Johannes Kepler
University Linz, Altenberger
Str. 69, 4040 Linz, Austria
| | - Daniel Huber
- Institute
of Experimental Physics, Johannes Kepler
University Linz, Altenberger
Str. 69, 4040 Linz, Austria
| | - Peter Zeppenfeld
- Institute
of Experimental Physics, Johannes Kepler
University Linz, Altenberger
Str. 69, 4040 Linz, Austria
| | - Eric Daniel Głowacki
- Linz
Institute for Organic Solar Cells (LIOS), Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| |
Collapse
|
11
|
Simbrunner C, Schwabegger G, Resel R, Dingemans T, Sitter H. The Epitaxial Growth of Self-Assembled Ternaphthalene Fibers on Muscovite Mica. CRYSTAL GROWTH & DESIGN 2014; 14:442-449. [PMID: 24526866 PMCID: PMC3919176 DOI: 10.1021/cg400912t] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 11/07/2013] [Indexed: 05/25/2023]
Abstract
The morphology and structure of 2,2':6',2″-ternaphthalene (NNN) deposited on muscovite mica(001) substrates was investigated by scanning force microscopy (SFM) and specular X-ray diffraction measurements. Consistently, both methods reveal the coexistence of needle-like structures with a {111} contact plane and {001} orientated island-like crystallites, which are built up by almost upright standing NNN molecules. Both orientations are characterized by a well-defined azimuthal alignment relative to the substrate surface, which is analyzed by X-ray diffraction pole figure (XRD-PF) measurements. Based on XRD-PF and SFM analysis, the azimuthal alignment of {001} orientated crystallites is explained by ledge-directed epitaxy along the fibers' sidewalls. These fibers are found to orient along two dominant directions, which is verified and explained by a doubling of the energetically preferred molecular adsorption site by mirror symmetry of the substrate surface. The experimental findings are confirmed by force-field simulations and are discussed based on a recently reported growth model.
Collapse
Affiliation(s)
- Clemens Simbrunner
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - Günther Schwabegger
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - Roland Resel
- Institute
of Solid State Physics, Graz University
of Technology, Petersgasse
16, A-8010 Graz, Austria
| | - Theo Dingemans
- Faculty
of Aerospace Engineering, Delft University
of Technology, 2629 HS Delft, The Netherlands
| | - Helmut Sitter
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz, Austria
| |
Collapse
|
12
|
Kjelstrup-Hansen J, Simbrunner C, Rubahn HG. Organic surface-grown nanowires for functional devices. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:126502. [PMID: 24262288 DOI: 10.1088/0034-4885/76/12/126502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Discontinuous organic thin film growth on the surface of single crystals results in crystalline nanowires with extraordinary morphological and optoelectronic properties. By way of being generated at the interface of organic and inorganic materials, these nanowires combine the advantages of flexible organic films with the defectless character of inorganic crystalline substrates. The development of destruction-free transfer and direct growth methods allows one to integrate the organic nanowires into semiconductor, metallic electronic or photonic platforms. This article details the mechanisms that lead to the growth of these nanowires and exemplifies some of the linear as well as non-linear photonic properties, such as optical wave guiding, lasing and frequency conversion. The article also highlights future potential by showing that organic nanowires can be integrated into optoelectronic devices or hybrid photonic/plasmonic platforms as passive and active nanoplasmonic elements.
Collapse
|
13
|
Schwabegger G, Oehzelt M, Salzmann I, Quochi F, Saba M, Mura A, Bongiovanni G, Vollmer A, Koch N, Sitter H, Simbrunner C. Interface properties of organic para-hexaphenyl/α-sexithiophene heterostructures deposited on highly oriented pyrolytic graphite. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:14444-14450. [PMID: 24156627 PMCID: PMC3842851 DOI: 10.1021/la402242b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 10/23/2013] [Indexed: 06/02/2023]
Abstract
It was recently reported, that heterostructures of para-hexaphenyl (p-6P) and α-sexithiophene (6T) deposited on muscovite mica exhibit the intriguing possibility to prepare lasing nanofibers of tunable emission wavelength. For p-6P/6T heterostructures, two different types of 6T emission have been observed, namely, the well-known red emission of bulk 6T crystals and additionally a green emission connected to the interface between p-6P and 6T. In this study, the origin of the green fluorescence is investigated by photoelectron spectroscopy (PES). As a prerequisite, it is necessary to prepare structurally similar organic crystals on a conductive surface, which leads to the choice of highly oriented pyrolytic graphite (HOPG) as a substrate. The similarity between p-6P/6T heterostructures on muscovite mica and on HOPG is evidenced by X-ray diffraction (XRD), scanning force microscopy (SFM), and optical spectroscopy. PES measurements show that the interface between p-6P and 6T crystals is sharp on a molecular level without any sign of interface dipole formation or chemical interaction between the molecules. We therefore conclude that the different emission colors of the two 6T phases are caused by different types of molecular aggregation.
Collapse
Affiliation(s)
- Günther Schwabegger
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - Martin Oehzelt
- Helmholtz
Zentrum Berlin für Materialien und Energie GmbH, BESSY II, D-12489 Berlin, Germany
- Institut
für Physik, Humboldt-Universität zu Berlin, D-12489 Berlin, Germany
| | - Ingo Salzmann
- Institut
für Physik, Humboldt-Universität zu Berlin, D-12489 Berlin, Germany
| | - Francesco Quochi
- Dipartimento
di Fisica, Università di Cagliari, I-09042 Monserrato
(CA), Italy
| | - Michele Saba
- Dipartimento
di Fisica, Università di Cagliari, I-09042 Monserrato
(CA), Italy
| | - Andrea Mura
- Dipartimento
di Fisica, Università di Cagliari, I-09042 Monserrato
(CA), Italy
| | - Giovanni Bongiovanni
- Dipartimento
di Fisica, Università di Cagliari, I-09042 Monserrato
(CA), Italy
- Istituto
Officina dei Materiali (CNR-IOM), Unità
di Cagliari, I-09042 Monserrato (CA), Italy
| | - Antje Vollmer
- Helmholtz
Zentrum Berlin für Materialien und Energie GmbH, BESSY II, D-12489 Berlin, Germany
| | - Norbert Koch
- Helmholtz
Zentrum Berlin für Materialien und Energie GmbH, BESSY II, D-12489 Berlin, Germany
- Institut
für Physik, Humboldt-Universität zu Berlin, D-12489 Berlin, Germany
| | - Helmut Sitter
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - Clemens Simbrunner
- Institute
of Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz, Austria
- Dipartimento
di Fisica, Università di Cagliari, I-09042 Monserrato
(CA), Italy
| |
Collapse
|
14
|
Novák J, Oehzelt M, Berkebile S, Koini M, Ules T, Koller G, Haber T, Resel R, Ramsey MG. Crystal growth of para-sexiphenyl on clean and oxygen reconstructed Cu(110) surfaces. Phys Chem Chem Phys 2011; 13:14675-84. [PMID: 21748174 DOI: 10.1039/c1cp20413k] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of crystalline para-sexiphenyl (6P) films on Cu(110) and Cu(110)-(2 × 1)O (Cu-O) has been studied by low energy electron diffraction, X-ray absorption spectroscopy and both in situ and ex situ X-ray diffraction methods to elucidate the transition from the initial monolayers to crystalline thin films. It is found that, for Cu-O, a single and, for Cu(110), a double wetting layer is formed which then acts as a template for the subsequent 3D crystal growth. For both substrates the orientation of the long molecular axes of the 6P molecules in the first layers is conserved for the molecules in the bulk crystals growing on them. The main difference between both systems is that on Cu-O the first monolayer assembles in a form close to that of a 6P bulk plane which can be easily continued by crystallites grown upon them, while on the Cu(110) surface the 6P mono- and bi-layers differ substantially from the bulk structure. The bi-layer forms a complex periodically striped phase. Thin 6P films grow with the 6P(203) crystal plane parallel to the Cu-O substrate surface. For this orientation, the 6P molecules are stacked in layers and the molecules demonstrate only one tilt of the mean molecular plane with respect to the sample surface. On clean Cu(110), a more complex 6P(629) plane is parallel to the substrate surface and this orientation is likely a consequence of the super-molecular long-range periodicity of the second molecular layer striped phase.
Collapse
Affiliation(s)
- Jiří Novák
- Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
| | | | | | | | | | | | | | | | | |
Collapse
|