1
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Self-assembly and photoinduced fabrication of conductive nanographene wires on boron nitride. Nat Commun 2022; 13:442. [PMID: 35064113 PMCID: PMC8782843 DOI: 10.1038/s41467-021-27600-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 11/17/2021] [Indexed: 11/12/2022] Open
Abstract
Manufacturing molecule-based functional elements directly at device interfaces is a frontier in bottom-up materials engineering. A longstanding challenge in the field is the covalent stabilization of pre-assembled molecular architectures to afford nanodevice components. Here, we employ the controlled supramolecular self-assembly of anthracene derivatives on a hexagonal boron nitride sheet, to generate nanographene wires through photo-crosslinking and thermal annealing. Specifically, we demonstrate µm-long nanowires with an average width of 200 nm, electrical conductivities of 106 S m−1 and breakdown current densities of 1011 A m−2. Joint experiments and simulations reveal that hierarchical self-assembly promotes their formation and functional properties. Our approach demonstrates the feasibility of combined bottom-up supramolecular templating and top-down manufacturing protocols for graphene nanomaterials and interconnects, towards integrated carbon nanodevices. The bottom-up fabrication of structures with robust performance in the nm-to-μm scale usable for integrated carbon nanodevices is challenging. Here the authors report micrometer-long, highly conducting nanographene wires following self-assembly, photo-crosslinking and thermal annealing of anthracene derivatives on hexagonal boron nitride sheets.
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2
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Zang Y, Fung ED, Fu T, Ray S, Garner MH, Borges A, Steigerwald ML, Patil S, Solomon G, Venkataraman L. Voltage-Induced Single-Molecule Junction Planarization. NANO LETTERS 2021; 21:673-679. [PMID: 33337876 DOI: 10.1021/acs.nanolett.0c04260] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Probing structural changes of a molecule induced by charge transfer is important for understanding the physicochemical properties of molecules and developing new electronic devices. Here, we interrogate the structural changes of a single diketopyrrolopyrrole (DPP) molecule induced by charge transport at a high bias using scanning tunneling microscope break junction (STM-BJ) techniques. Specifically, we demonstrate that application of a high bias increases the average nonresonant conductance of single Au-DPP-Au junctions. We infer from the increased conductance that resonant charge transport induces planarization of the molecular backbone. We further show that this conformational planarization is assisted by thermally activated junction reorganization. The planarization only occurs under specific electronic conditions, which we rationalize by ab initio calculations. These results emphasize the need for a comprehensive view of single-molecule junctions which includes both the electronic properties and structure of the molecules and the electrodes when designing electrically driven single-molecule motors.
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Affiliation(s)
- Yaping Zang
- Department of Applied Physics, Columbia University, New York, New York 10027, United States
| | - E-Dean Fung
- Department of Applied Physics, Columbia University, New York, New York 10027, United States
| | - Tianren Fu
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Suman Ray
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Marc H Garner
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen Ø DK-2100, Denmark
| | - Anders Borges
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen Ø DK-2100, Denmark
| | - Michael L Steigerwald
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Satish Patil
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Gemma Solomon
- Nano-Science Center and Department of Chemistry, University of Copenhagen, Copenhagen Ø DK-2100, Denmark
| | - Latha Venkataraman
- Department of Applied Physics, Columbia University, New York, New York 10027, United States
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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3
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Patera LL, Queck F, Repp J. Imaging Charge Localization in a Conjugated Oligophenylene. PHYSICAL REVIEW LETTERS 2020; 125:176803. [PMID: 33156651 DOI: 10.1103/physrevlett.125.176803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/23/2020] [Accepted: 09/08/2020] [Indexed: 06/11/2023]
Abstract
Polaron formation in conjugated polymers has a major impact on their optical and electronic properties. In polyphenylene, the molecular conformation is determined by a delicate interplay between electron delocalization and steric effects. Injection of excess charges is expected to increase the degree of conjugation, leading to structural distortions of the chain. Here we investigated at the single-molecule level the role of an excess charge in an individual oligophenylene deposited on sodium chloride films. By combining sub-molecular-resolved atomic force microscopy with redox-state-selective orbital imaging, we characterize both structural and electronical changes occurring upon hole injection. While the neutral molecule exhibits a delocalized frontier orbital, for the cationic radical the excess charge is observed to localize, inducing a partial planarization of the molecule. These results provide direct evidence for self-trapping of the excess charge in oligophenylenes, shedding light on the interplay of charge localization and structural distortion.
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Affiliation(s)
- Laerte L Patera
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Fabian Queck
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Jascha Repp
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
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4
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Rothe K, Mehler A, Néel N, Kröger J. Scanning tunneling microscopy and spectroscopy of rubrene on clean and graphene-covered metal surfaces. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1157-1167. [PMID: 32821640 PMCID: PMC7418095 DOI: 10.3762/bjnano.11.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
Rubrene (C42H28) was adsorbed with submonolayer coverage on Pt(111), Au(111), and graphene-covered Pt(111). Adsorption phases and vibronic properties of C42H28 consistently reflect the progressive reduction of the molecule-substrate hybridization. Separate C42H28 clusters are observed on Pt(111) as well as broad molecular resonances. On Au(111) and graphene-covered Pt(111) compact molecular islands with similar unit cells of the superstructure characterize the adsorption phase. The highest occupied molecular orbital of C42H28 on Au(111) exhibits weak vibronic progression while unoccupied molecular resonances appear with a broad line shape. In contrast, vibronic subbands are present for both frontier orbitals of C42H28 on graphene. They are due to different molecular vibrational quanta with distinct Huang-Rhys factors.
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Affiliation(s)
- Karl Rothe
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Alexander Mehler
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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5
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Mehler A, Néel N, Kröger J. Dissimilar Decoupling Behavior of Two-Dimensional Materials on Metal Surfaces. J Phys Chem Lett 2020; 11:5204-5211. [PMID: 32515963 DOI: 10.1021/acs.jpclett.0c01320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The efficiency of hexagonal boron nitride and graphene to separate the hydrocarbon molecule C64H36 from Ru(0001) and Pt(111) surfaces is explored in low-temperature scanning tunneling microscopy and spectroscopy experiments. Both 2D materials enable the observation of the Franck-Condon effect in both frontier orbitals. On hexagonal boron nitride, vibronic progression with two vibrational energies gives rise to sharp orbital sidebands that are clearly visible up to the second order of the vibrational quantum number with different Huang-Rhys factors. In contrast, on graphene, orbital and vibronic spectroscopic signatures exhibit broad line shapes, with the second-order progression being hardly discriminable. Only a single vibrational quantum energy leaves its fingerprint in the Franck-Condon spectrum.
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Affiliation(s)
- Alexander Mehler
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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6
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Zimmermann DM, Seufert K, Ðorđević L, Hoh T, Joshi S, Marangoni T, Bonifazi D, Auwärter W. Self-assembly and spectroscopic fingerprints of photoactive pyrenyl tectons on hBN/Cu(111). BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1470-1483. [PMID: 33083195 PMCID: PMC7537405 DOI: 10.3762/bjnano.11.130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 09/03/2020] [Indexed: 05/06/2023]
Abstract
The controlled modification of electronic and photophysical properties of polycyclic aromatic hydrocarbons by chemical functionalization, adsorption on solid supports, and supramolecular organization is the key to optimize the application of these compounds in (opto)electronic devices. Here, we present a multimethod study comprehensively characterizing a family of pyridin-4-ylethynyl-functionalized pyrene derivatives in different environments. UV-vis measurements in toluene solutions revealed absorption at wavelengths consistent with density functional theory (DFT) calculations, while emission experiments showed a high fluorescence quantum yield. Scanning tunneling microscopy (STM) and spectroscopy (STS) measurements of the pyrene derivatives adsorbed on a Cu(111)-supported hexagonal boron nitride (hBN) decoupling layer provided access to spatially and energetically resolved molecular electronic states. We demonstrate that the pyrene electronic gap is reduced with an increasing number of substituents. Furthermore, we discuss the influence of template-induced gating and supramolecular organization on the energies of distinct molecular orbitals. The selection of the number and positioning of the pyridyl termini in tetrasubstituted, trans- and cis-like-disubstituted derivatives governed the self-assembly of the pyrenyl core on the nanostructured hBN support, affording dense-packed arrays and intricate porous networks featuring a kagome lattice.
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Affiliation(s)
- Domenik M Zimmermann
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
| | - Knud Seufert
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
| | - Luka Ðorđević
- The School of Chemistry, Cardiff University, UK-CF10 3AT Cardiff, United Kingdom
| | - Tobias Hoh
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
| | - Sushobhan Joshi
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
| | - Tomas Marangoni
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, I-34127 Trieste, Italy
| | - Davide Bonifazi
- The School of Chemistry, Cardiff University, UK-CF10 3AT Cardiff, United Kingdom
- Institute of Organic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 38, 1090 Vienna, Austria
| | - Willi Auwärter
- Physics Department E20, Technical University of Munich, James-Franck-Straße 1, D-85748 Garching, Germany
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7
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Cojal González JD, Li J, Stöhr M, Kivala M, Palma CA, Rabe JP. Edge Phonon Excitations in a Chiral Self-Assembled Supramolecular Nanoribbon. J Phys Chem Lett 2019; 10:5830-5835. [PMID: 31535863 DOI: 10.1021/acs.jpclett.9b02001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
By design, coupled mechanical oscillators offer a playground for the study of crystalline topology and related properties. Particularly, non-centrosymmetric, supramolecular nanocrystals feature a complex phonon spectrum where edge modes may evolve. Here we show, employing classical atomistic calculations, that the edges of a chiral supramolecular nanoribbon can host defined edge phonon states. We suggest that the topology of several edge modes in the phonon spectrum is nontrivial and thermally insulated from bulk states. By means of molecular dynamics, we excite a supramolecular bond to launch a directional excitation along the edge without considerable bulk or back-propagation. Our results suggest that supramolecular monolayers can be employed to engineer phonon states that are robust against backscattering, toward supramolecular thermal waveguides, diodes, and logics.
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Affiliation(s)
- José D Cojal González
- Department of Physics & IRIS Adlershof , Humboldt-Universität zu Berlin , Newtonstr. 15 , 12489 Berlin , Germany
| | - Juan Li
- Institute of Physics , Chinese Academy of Sciences , 10090 Beijing , P.R. China
- Advanced Research Institute of Multidisciplinary Science , Beijing Institute of Technology , 100081 Beijing , P.R. China
| | - Meike Stöhr
- Zernike Institute for Advanced Materials , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Milan Kivala
- Organisch-Chemisches Institut & Centre for Advanced Materials , Ruprecht-Karls-Universität Heidelberg , Im Neuenheimer Feld 270 & 225 , 69120 Heidelberg , Germany
| | - Carlos-Andres Palma
- Department of Physics & IRIS Adlershof , Humboldt-Universität zu Berlin , Newtonstr. 15 , 12489 Berlin , Germany
- Institute of Physics , Chinese Academy of Sciences , 10090 Beijing , P.R. China
| | - Jürgen P Rabe
- Department of Physics & IRIS Adlershof , Humboldt-Universität zu Berlin , Newtonstr. 15 , 12489 Berlin , Germany
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8
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Mehler A, Néel N, Bocquet ML, Kröger J. Exciting vibrons in both frontier orbitals of a single hydrocarbon molecule on graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:065001. [PMID: 30523960 DOI: 10.1088/1361-648x/aaf54c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Vibronic excitations in molecules are key to the fundamental understanding of the interaction between vibrational and electronic degrees of freedom. In order to probe the genuine vibronic properties of a molecule even after its adsorption on a surface appropriate buffer layers are of paramount importance. Here, vibrational progression in both molecular frontier orbitals is observed with submolecular resolution on a graphene-covered metal surface using scanning tunnelling spectroscopy. Accompanying calculations demonstrate that the vibrational modes that cause the orbital replica in the progression share the same symmetry as the electronic states they couple to. In addition, the vibrational progression is more pronounced for separated molecules than for molecules embedded in molecular assemblies. The entire vibronic spectra of these molecular species are moreover rigidly shifted with respect to each other. This work unravels intramolecular changes in the vibronic and electronic structure owing to the efficient reduction of the molecule-metal hybridization by graphene.
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Affiliation(s)
- A Mehler
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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9
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Schwarz M, Duncan DA, Garnica M, Ducke J, Deimel PS, Thakur PK, Lee TL, Allegretti F, Auwärter W. Quantitative determination of a model organic/insulator/metal interface structure. NANOSCALE 2018; 10:21971-21977. [PMID: 30444513 PMCID: PMC6289171 DOI: 10.1039/c8nr06387g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 09/28/2018] [Indexed: 05/22/2023]
Abstract
By combining X-ray photoelectron spectroscopy, X-ray standing waves and scanning tunneling microscopy, we investigate the geometric and electronic structure of a prototypical organic/insulator/metal interface, namely cobalt porphine on monolayer hexagonal boron nitride (h-BN) on Cu(111). Specifically, we determine the adsorption height of the organic molecule and show that the original planar molecular conformation is preserved in contrast to the adsorption on Cu(111). In addition, we highlight the electronic decoupling provided by the h-BN spacer layer and find that the h-BN-metal separation is not significantly modified by the molecular adsorption. Finally, we find indication of a temperature dependence of the adsorption height, which might be a signature of strongly-anisotropic thermal vibrations of the weakly bonded molecules.
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Affiliation(s)
- Martin Schwarz
- Physics Department
, Technical University of Munich
,
85748 Garching
, Germany
.
;
| | - David A. Duncan
- Diamond Light Source
, Harwell Science and Innovation Campus
,
Didcot OX11 0DE
, UK
| | - Manuela Garnica
- Physics Department
, Technical University of Munich
,
85748 Garching
, Germany
.
;
| | - Jacob Ducke
- Physics Department
, Technical University of Munich
,
85748 Garching
, Germany
.
;
| | - Peter S. Deimel
- Physics Department
, Technical University of Munich
,
85748 Garching
, Germany
.
;
| | - Pardeep K. Thakur
- Diamond Light Source
, Harwell Science and Innovation Campus
,
Didcot OX11 0DE
, UK
| | - Tien-Lin Lee
- Diamond Light Source
, Harwell Science and Innovation Campus
,
Didcot OX11 0DE
, UK
| | - Francesco Allegretti
- Physics Department
, Technical University of Munich
,
85748 Garching
, Germany
.
;
| | - Willi Auwärter
- Physics Department
, Technical University of Munich
,
85748 Garching
, Germany
.
;
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10
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Bi H, Palma CA, Gong Y, Hasch P, Elbing M, Mayor M, Reichert J, Barth JV. Voltage-Driven Conformational Switching with Distinct Raman Signature in a Single-Molecule Junction. J Am Chem Soc 2018; 140:4835-4840. [DOI: 10.1021/jacs.7b12818] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Hai Bi
- Physics Department E20, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Carlos-Andres Palma
- Physics Department E20, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
- Institute of Physics, Chinese Academy of Sciences, 100190 Beijing, P.R. China
| | - Yuxiang Gong
- Physics Department E20, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Peter Hasch
- Physics Department E20, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Mark Elbing
- Department of Applied Natural Sciences, Lübeck University of Applied Sciences, Mönkhofer Weg 239, 23562 Lübeck, Germany
| | - Marcel Mayor
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Karlsruhe, Germany
- Department of Chemistry, University of Basel, St Johannsring 19, CH-4056 Basel, Switzerland
| | - Joachim Reichert
- Physics Department E20, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
| | - Johannes V. Barth
- Physics Department E20, Technical University of Munich, James-Franck-Str. 1, 85748 Garching, Germany
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11
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Makarova MV, Okawa Y, Verveniotis E, Watanabe K, Taniguchi T, Joachim C, Aono M. Self-assembled diacetylene molecular wire polymerization on an insulating hexagonal boron nitride (0001) surface. NANOTECHNOLOGY 2016; 27:395303. [PMID: 27573286 DOI: 10.1088/0957-4484/27/39/395303] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The electrical characterization of single-polymer chains on a surface is an important step towards novel molecular device development. The main challenge is the lack of appropriate atomically flat insulating substrates for fabricating single-polymer chains. Here, using atomic force microscopy, we demonstrate that the (0001) surface of an insulating hexagonal boron nitride (h-BN) substrate leads to a flat-lying self-assembled monolayer of diacetylene compounds. The subsequent heating or ultraviolet irradiation can initiate an on-surface polymerization process leading to the formation of long polydiacetylene chains. The frequency of photo-polymerization occurrence on h-BN(0001) is two orders of magnitude higher than that on graphite(0001). This is explained by the enhanced lifetime of the molecular excited state, because relaxation via the h-BN is suppressed due to a large band gap. We also demonstrate that on-surface polymerization on h-BN(0001) is possible even after the lithography process, which opens up the possibility of further electrical investigations.
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Affiliation(s)
- Marina V Makarova
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. Institute of Physics, Czech Academy of Sciences, Na Slovance, 2, Prague 8, 18221, Czech Republic
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12
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Urgel JI, Schwarz M, Garnica M, Stassen D, Bonifazi D, Ecija D, Barth JV, Auwärter W. Controlling Coordination Reactions and Assembly on a Cu(111) Supported Boron Nitride Monolayer. J Am Chem Soc 2015; 137:2420-3. [DOI: 10.1021/ja511611r] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- José I. Urgel
- Physik
Department E20, Technische Universität München, James
Franck Str. 1, D-85748 Garching, Germany
| | - Martin Schwarz
- Physik
Department E20, Technische Universität München, James
Franck Str. 1, D-85748 Garching, Germany
| | - Manuela Garnica
- Physik
Department E20, Technische Universität München, James
Franck Str. 1, D-85748 Garching, Germany
| | - Daphné Stassen
- Department
of Chemistry and Namur Research College (NARC), University of Namur (UNamur), Namur, Belgium
| | - Davide Bonifazi
- Department
of Chemistry and Namur Research College (NARC), University of Namur (UNamur), Namur, Belgium
| | - David Ecija
- Physik
Department E20, Technische Universität München, James
Franck Str. 1, D-85748 Garching, Germany
- IMDEA Nanoscience, 28049 Madrid, Spain
| | - Johannes V. Barth
- Physik
Department E20, Technische Universität München, James
Franck Str. 1, D-85748 Garching, Germany
| | - Willi Auwärter
- Physik
Department E20, Technische Universität München, James
Franck Str. 1, D-85748 Garching, Germany
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