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Cortés-Del Río E, Trivini S, Pascual JI, Cherkez V, Mallet P, Veuillen JY, Cuevas JC, Brihuega I. Shaping Graphene Superconductivity with Nanometer Precision. Small 2024; 20:e2308439. [PMID: 38112230 DOI: 10.1002/smll.202308439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 11/23/2023] [Indexed: 12/21/2023]
Abstract
Graphene holds great potential for superconductivity due to its pure 2D nature, the ability to tune its carrier density through electrostatic gating, and its unique, relativistic-like electronic properties. At present, still far from controlling and understanding graphene superconductivity, mainly because the selective introduction of superconducting properties to graphene is experimentally very challenging. Here, a method is developed that enables shaping at will graphene superconductivity through a precise control of graphene-superconductor junctions. The method combines the proximity effect with scanning tunnelling microscope (STM) manipulation capabilities. Pb nano-islands are first grown that locally induce superconductivity in graphene. Using a STM, Pb nano-islands can be selectively displaced, over different types of graphene surfaces, with nanometre scale precision, in any direction, over distances of hundreds of nanometres. This opens an exciting playground where a large number of predefined graphene-superconductor hybrid structures can be investigated with atomic scale precision. To illustrate the potential, a series of experiments are performed, rationalized by the quasi-classical theory of superconductivity, going from the fundamental understanding of superconductor-graphene-superconductor heterostructures to the construction of superconductor nanocorrals, further used as "portable" experimental probes of local magnetic moments in graphene.
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Affiliation(s)
- Eva Cortés-Del Río
- Departamento Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, E-28049, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, E-28049, Spain
| | | | - José I Pascual
- CIC nanoGUNE-BRTA, Donostia-San Sebastián, 20018, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, 48013, Spain
| | - Vladimir Cherkez
- Université Grenoble Alpes, CNRS, Institut Néel, Grenoble, F-38400, France
- CNRS, Institut Neel, Grenoble, F-38042, France
| | - Pierre Mallet
- Université Grenoble Alpes, CNRS, Institut Néel, Grenoble, F-38400, France
- CNRS, Institut Neel, Grenoble, F-38042, France
| | - Jean-Yves Veuillen
- Université Grenoble Alpes, CNRS, Institut Néel, Grenoble, F-38400, France
- CNRS, Institut Neel, Grenoble, F-38042, France
| | - Juan C Cuevas
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, E-28049, Spain
- Departamento Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, E-28049, Spain
- Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid, E-28049, Spain
| | - Iván Brihuega
- Departamento Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, E-28049, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, E-28049, Spain
- Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Madrid, E-28049, Spain
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2
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Brede J, Merino-Díez N, Berdonces-Layunta A, Sanz S, Domínguez-Celorrio A, Lobo-Checa J, Vilas-Varela M, Peña D, Frederiksen T, Pascual JI, de Oteyza DG, Serrate D. Detecting the spin-polarization of edge states in graphene nanoribbons. Nat Commun 2023; 14:6677. [PMID: 37865684 PMCID: PMC10590394 DOI: 10.1038/s41467-023-42436-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 10/11/2023] [Indexed: 10/23/2023] Open
Abstract
Low dimensional carbon-based materials can show intrinsic magnetism associated to p-electrons in open-shell π-conjugated systems. Chemical design provides atomically precise control of the π-electron cloud, which makes them promising for nanoscale magnetic devices. However, direct verification of their spatially resolved spin-moment remains elusive. Here, we report the spin-polarization of chiral graphene nanoribbons (one-dimensional strips of graphene with alternating zig-zag and arm-chair boundaries), obtained by means of spin-polarized scanning tunnelling microscopy. We extract the energy-dependent spin-moment distribution of spatially extended edge states with π-orbital character, thus beyond localized magnetic moments at radical or defective carbon sites. Guided by mean-field Hubbard calculations, we demonstrate that electron correlations are responsible for the spin-splitting of the electronic structure. Our versatile platform utilizes a ferromagnetic substrate that stabilizes the organic magnetic moments against thermal and quantum fluctuations, while being fully compatible with on-surface synthesis of the rapidly growing class of nanographenes.
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Grants
- E13-20R Gobierno de Aragón
- E12-20R Gobierno de Aragón
- ED431G2019/03 Xunta de Galicia
- 863098 EC | EU Framework Programme for Research and Innovation H2020 | H2020 Priority Excellent Science | H2020 Future and Emerging Technologies (H2020 Excellent Science - Future and Emerging Technologies)
- PRE-2021-2-0190 Eusko Jaurlaritza (Basque Government)
- PIBA-2020-1-0014 Eusko Jaurlaritza (Basque Government)
- 863098 EC | EU Framework Programme for Research and Innovation H2020 | H2020 Priority Excellent Science | H2020 Future and Emerging Technologies (H2020 Excellent Science - Future and Emerging Technologies)
- Ministerio de Ciencia, Innovación y Universidades | Agencia Estatal de Investigación, Grant no PID2019-107338RB-C64 Eureopean Comission | European Regional Developement Funds | Interreg, Grant no EFA194/16 TNSI
- Ministerio de Ciencia, Innovación y Universidades | Agencia Estatal de Investigación, Grant no PID2019-107338RB-C64
- Ministerio de Ciencia, Innovación y Universidades | Agencia Estatal de Investigación, Grant no PID2019-107338RB-C62
- Ministerio de Ciencia, Innovación y Universidades | Agencia Estatal de Investigación, Grant no PID2020–115406GB-I00
- Ministerio de Ciencia, Innovación y Universidades | Agencia Estatal de Investigación, Grant no PID2019-107338RB-C61 Maria de Maeztu Excellence Program, Grant no CEX2020-001038-M Diputación Foral de Guipuzkoa | Guipuzkoa Next, grant no 2021-CIEN-000069-01
- Ministerio de Ciencia, Innovación y Universidades | Agencia Estatal de Investigación, Grant no PID2019-107338RB-C63
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Affiliation(s)
- Jens Brede
- Donostia International Physics Center, San Sebastián, E-20018, Spain
- Centro de Física de Materiales (MPC), CSIC-UPV/EHU, San Sebastián, E-20018, Spain
| | - Nestor Merino-Díez
- Donostia International Physics Center, San Sebastián, E-20018, Spain
- Centro de Física de Materiales (MPC), CSIC-UPV/EHU, San Sebastián, E-20018, Spain
| | - Alejandro Berdonces-Layunta
- Donostia International Physics Center, San Sebastián, E-20018, Spain
- Centro de Física de Materiales (MPC), CSIC-UPV/EHU, San Sebastián, E-20018, Spain
| | - Sofía Sanz
- Donostia International Physics Center, San Sebastián, E-20018, Spain
| | - Amelia Domínguez-Celorrio
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, E-50009, Spain
| | - Jorge Lobo-Checa
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, E-50009, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, E-50009, Spain
- Laboratorio de Microscopias Avanzadas (LMA), Universidad de Zaragoza, Zaragoza, E-50009, Spain
| | - Manuel Vilas-Varela
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela, E-15782, Spain
| | - Diego Peña
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela, E-15782, Spain
| | - Thomas Frederiksen
- Donostia International Physics Center, San Sebastián, E-20018, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, E-48013, Spain
| | - José I Pascual
- Ikerbasque, Basque Foundation for Science, Bilbao, E-48013, Spain.
- CIC nanoGUNE BRTA, San Sebastián, E-20018, Spain.
| | - Dimas G de Oteyza
- Donostia International Physics Center, San Sebastián, E-20018, Spain.
- Centro de Física de Materiales (MPC), CSIC-UPV/EHU, San Sebastián, E-20018, Spain.
- Nanomaterials and Nanotechnology Research Center (CINN), CSIC-UNIOVI-PA, El Entrego, E-33940, Spain.
| | - David Serrate
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, E-50009, Spain.
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, E-50009, Spain.
- Laboratorio de Microscopias Avanzadas (LMA), Universidad de Zaragoza, Zaragoza, E-50009, Spain.
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3
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Bachellier N, Verlhac B, Garnier L, Zaldívar J, Rubio-Verdú C, Abufager P, Ormaza M, Choi DJ, Bocquet ML, Pascual JI, Lorente N, Limot L. Vibron-assisted spin excitation in a magnetically anisotropic molecule. Nat Commun 2020; 11:1619. [PMID: 32238814 PMCID: PMC7113279 DOI: 10.1038/s41467-020-15266-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 02/21/2020] [Indexed: 11/09/2022] Open
Abstract
The electrical control and readout of molecular spin states are key for high-density storage. Expectations are that electrically-driven spin and vibrational excitations in a molecule should give rise to new conductance features in the presence of magnetic anisotropy, offering alternative routes to study and, ultimately, manipulate molecular magnetism. Here, we use inelastic electron tunneling spectroscopy to promote and detect the excited spin states of a prototypical molecule with magnetic anisotropy. We demonstrate the existence of a vibron-assisted spin excitation that can exceed in energy and in amplitude a simple excitation among spin states. This excitation, which can be quenched by structural changes in the magnetic molecule, is explained using first-principles calculations that include dynamical electronic correlations.
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Affiliation(s)
- N Bachellier
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000, Strasbourg, France
| | - B Verlhac
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000, Strasbourg, France.
| | - L Garnier
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000, Strasbourg, France
| | - J Zaldívar
- CIC nanoGUNE, 20018, Donostia-San Sebastián, Spain
| | | | - P Abufager
- Instituto de Física de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Universidad Nacional de Rosario, Av. Pellegrini 250 (2000), Rosario, Argentina
| | - M Ormaza
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000, Strasbourg, France
- Universidad del País Vasco, Dpto. Física Aplicada I, 20018, Donostia-San Sebastián, Spain
| | - D-J Choi
- Centro de Física de Materiales (CFM MPC) CSIC-EHU, 20018, Donostia-San San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - M-L Bocquet
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, PSL University, Sorbonne Universités, CNRS, 24 Rue Lhomond, 75005, Paris, France
| | - J I Pascual
- CIC nanoGUNE, 20018, Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - N Lorente
- Centro de Física de Materiales (CFM MPC) CSIC-EHU, 20018, Donostia-San San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain
| | - L Limot
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000, Strasbourg, France.
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4
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Guster B, Rubio-Verdú C, Robles R, Zaldívar J, Dreher P, Pruneda M, Silva-Guillén JÁ, Choi DJ, Pascual JI, Ugeda MM, Ordejón P, Canadell E. Coexistence of Elastic Modulations in the Charge Density Wave State of 2 H-NbSe 2. Nano Lett 2019; 19:3027-3032. [PMID: 30998364 DOI: 10.1021/acs.nanolett.9b00268] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Bulk and single-layer 2 H-NbSe2 exhibit identical charge density wave order (CDW) with a quasi-commensurate 3 × 3 superlattice periodicity. Here we combine scanning tunnelling microscopy (STM) imaging at T = 1 K of 2 H-NbSe2 with first-principles density functional theory (DFT) calculations to investigate the structural atomic rearrangement of this CDW phase. Our calculations for single-layers reveal that six different atomic structures are compatible with the 3 × 3 CDW distortion, although all of them lie on a very narrow energy range of at most 3 meV per formula unit, suggesting the coexistence of such structures. Our atomically resolved STM images of bulk 2 H-NbSe2 unambiguously confirm this by identifying two of these structures. Remarkably, these structures differ from the X-ray crystal structure reported for the bulk 3 × 3 CDW which in fact is also one of the six DFT structures located for the single-layer. Our calculations also show that due to the minute energy difference between the different phases, the ground state of the 3 × 3 CDW could be extremely sensitive to doping, external strain or internal pressure within the crystal. The presence of multiphase CDW order in 2 H-NbSe2 may provide further understanding of its low temperature state and the competition between different instabilities.
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Affiliation(s)
- Bogdan Guster
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona , Spain
| | | | - Roberto Robles
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona , Spain
| | | | - Paul Dreher
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizábal 4 , 20018 San Sebastián , Spain
- Centro de Física de Materiales (CSIC-UPV-EHU) , Manuel Lardizábal 4 , 20018 San Sebastián , Spain
| | - Miguel Pruneda
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona , Spain
| | | | - Deung-Jang Choi
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizábal 4 , 20018 San Sebastián , Spain
- Centro de Física de Materiales (CSIC-UPV-EHU) , Manuel Lardizábal 4 , 20018 San Sebastián , Spain
- Ikerbasque, Basque Foundation for Science , 48013 Bilbao , Spain
| | - José I Pascual
- CIC nanoGUNE , 20018 San Sebastián , Spain
- Ikerbasque, Basque Foundation for Science , 48013 Bilbao , Spain
| | - Miguel M Ugeda
- CIC nanoGUNE , 20018 San Sebastián , Spain
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizábal 4 , 20018 San Sebastián , Spain
- Centro de Física de Materiales (CSIC-UPV-EHU) , Manuel Lardizábal 4 , 20018 San Sebastián , Spain
- Ikerbasque, Basque Foundation for Science , 48013 Bilbao , Spain
| | - Pablo Ordejón
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona , Spain
| | - Enric Canadell
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , Campus UAB , 08193 Bellaterra , Spain
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5
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Yang Z, Lotze C, Corso M, Baum S, Franke KJ, Pascual JI. Direct Imaging of the Induced-Fit Effect in Molecular Self-Assembly. Small 2019; 15:e1804713. [PMID: 30748106 DOI: 10.1002/smll.201804713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 01/24/2019] [Indexed: 06/09/2023]
Abstract
Molecular recognition is a crucial driving force for molecular self-assembly. In many cases molecules arrange in the lowest energy configuration following a lock-and-key principle. When molecular flexibility comes into play, the induced-fit effect may govern the self-assembly. Here, the self-assembly of dicyanovinyl-hexathiophene (DCV6T) molecules, a prototype specie for highly efficient organic solar cells, on Au(111) by using low-temperature scanning tunneling microscopy and atomic force microscopy is investigated. DCV6T molecules assemble on the surface forming either islands or chains. In the islands the molecules are straight-the lowest energy configuration in gas phase-and expose the dicyano moieties to form hydrogen bonds with neighbor molecules. In contrast, the structure of DCV6T molecules in the chain assemblies deviates significantly from their gas-phase analogues. The seemingly energetically unfavorable bent geometry is enforced by hydrogen-bonding intermolecular interactions. Density functional theory calculations of molecular dimers quantitatively demonstrate that the deformation of individual molecules optimizes the intermolecular bonding structure. The intermolecular bonding energy thus drives the chain structure formation, which is an expression of the induced-fit effect.
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Affiliation(s)
- Zechao Yang
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Christian Lotze
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Martina Corso
- Centro de Física de Materiales (CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastian, Spain
| | - Sebastian Baum
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Katharina J Franke
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - José I Pascual
- CIC nanoGUNE and Ikerbaske, Basque Foundation for Science, Tolosa Hiribidea 76, 20018, Donostia San Sebastian, Spain
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6
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Heinrich BW, Ahmadi G, Müller VL, Braun L, Pascual JI, Franke KJ. Change of the magnetic coupling of a metal-organic complex with the substrate by a stepwise ligand reaction. Nano Lett 2013; 13:4840-3. [PMID: 23985020 DOI: 10.1021/nl402575c] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The surface-assisted intramolecular ligand reaction of a porphyrin molecule adsorbed on Au(111) is studied by scanning tunneling microscopy and spectroscopy. The temperature-induced stepwise transformation of iron octaethylporphyrin proceeds via a concentric electrocyclic ring closure, with the final product iron tetrabenzoporphyrin being identified by its characteristic Kondo resonance. Along with the transformation of the organic ligand, changes in the magnetic fingerprint are observed, indicating an increasing coupling of the iron spin with the substrate electrons.
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Affiliation(s)
- Benjamin W Heinrich
- Institut für Experimentalphysik, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
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7
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Umbach TR, Bernien M, Hermanns CF, Krüger A, Sessi V, Fernandez-Torrente I, Stoll P, Pascual JI, Franke KJ, Kuch W. Ferromagnetic coupling of mononuclear Fe centers in a self-assembled metal-organic network on Au(111). Phys Rev Lett 2012; 109:267207. [PMID: 23368613 DOI: 10.1103/physrevlett.109.267207] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Indexed: 06/01/2023]
Abstract
The magnetic state and magnetic coupling of individual atoms in nanoscale structures relies on a delicate balance between different interactions with the atomic-scale surroundings. Using scanning tunneling microscopy, we resolve the self-assembled formation of highly ordered bilayer structures of Fe atoms and organic linker molecules (T4PT) when deposited on a Au(111) surface. The Fe atoms are encaged in a three-dimensional coordination motif by three T4PT molecules in the surface plane and an additional T4PT unit on top. Within this crystal field, the Fe atoms retain a magnetic ground state with easy-axis anisotropy, as evidenced by x-ray absorption spectroscopy and x-ray magnetic circular dichroism. The magnetization curves reveal the existence of ferromagnetic coupling between the Fe centers.
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Affiliation(s)
- T R Umbach
- Freie Universität Berlin, Fachbereich Physik, Arnimallee 14, 14195 Berlin, Germany
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8
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Stróżecka A, Soriano M, Pascual JI, Palacios JJ. Reversible change of the spin state in a manganese phthalocyanine by coordination of CO molecule. Phys Rev Lett 2012; 109:147202. [PMID: 23083274 DOI: 10.1103/physrevlett.109.147202] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Indexed: 06/01/2023]
Abstract
We show that the magnetic state of individual manganese phthalocyanine (MnPc) molecules on a Bi(110) surface is modified when the Mn2+ center coordinates to CO molecules adsorbed on top. Using scanning tunneling spectroscopy we identified this change in magnetic properties from the broadening of a Kondo-related zero-bias anomaly when the CO-MnPc complex is formed. The original magnetic state can be recovered by selective desorption of individual CO molecules. First principles calculations show that the CO molecule reduces the spin of the adsorbed MnPc from S=1 to S=1/2 and strongly modifies the respective screening channels, driving a transition from an underscreened Kondo state to a state of mixed valence.
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Affiliation(s)
- A Stróżecka
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
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9
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Lotze C, Luo Y, Corso M, Franke KJ, Haag R, Pascual JI. Reversible electron-induced cis-trans isomerization mediated by intermolecular interactions. J Phys Condens Matter 2012; 24:394016. [PMID: 22964587 DOI: 10.1088/0953-8984/24/39/394016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Reversible isomerization processes are rarely found when organic molecular switches are adsorbed on metal surfaces. One obstacle is the large energy difference of the isomeric forms, since usually the most planar conformer has the largest adsorption energy. In the example of an imine derivative, we show a strategy for also stabilizing the non-planar isomer by intermolecular bonding to its neighbors. Tunneling electrons from the tip of a scanning tunneling microscope can then be used to induce reversible switching between the trans and cis-like state. Supported by model force-field calculations, we illustrate that the most probable cause of the enhanced stability of the three-dimensional cis state at specific adsorption sites is the electrostatic interaction with N sites of the neighboring molecule.
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Affiliation(s)
- Ch Lotze
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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10
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Umbach TR, Fernandez-Torrente I, Ladenthin JN, Pascual JI, Franke KJ. Enhanced charge transfer in a monolayer of the organic charge transfer complex TTF-TNAP on Au(111). J Phys Condens Matter 2012; 24:354003. [PMID: 22898901 DOI: 10.1088/0953-8984/24/35/354003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Electronic doping is a key concept for tuning the properties of organic materials. In bulk structures, the charge transfer between donor and acceptor is mainly given by the respective ionization potential and electron affinity. In contrast, monolayers of charge transfer complexes in contact with a metal are affected by an intriguing interplay of hybridization and screening at the metallic interface, determining the resulting charge state. Using scanning tunneling microscopy and spectroscopy, we characterize the electronic properties of the organic acceptor molecule 11,11,12,12-tetracyanonaptho-2,6-quinodimethane (TNAP) adsorbed on a Au(111) surface. The ordered islands remain in a weakly physisorbed state with no charge transfer interaction with the substrate. When the electron donor tetrathiafulvalene (TTF) is added, ordered arrays of alternating TNAP and TTF rows are assembled. In these structures, we find the lowest unoccupied molecular orbital (LUMO) of the free TNAP molecule shifted well below the Fermi level of the substrate. The TNAP is thus charged with more than one electron.
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Affiliation(s)
- T R Umbach
- Freie Universität Berlin, Fachbereich Physik, Berlin, Germany
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11
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Fernández-Torrente I, Kreikemeyer-Lorenzo D, Stróżecka A, Franke KJ, Pascual JI. Gating the charge state of single molecules by local electric fields. Phys Rev Lett 2012; 108:036801. [PMID: 22400769 DOI: 10.1103/physrevlett.108.036801] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Indexed: 05/31/2023]
Abstract
The electron-acceptor molecule TCNQ is found in either of two distinct integer charge states when embedded into a monolayer of a charge transfer complex on a gold surface. Scanning tunneling spectroscopy measurements identify these states through the presence or absence of a zero-bias Kondo resonance. Increasing the (tip-induced) electric field allows us to reversibly induce the oxidation or reduction of TCNQ species from their anionic or neutral ground state, respectively. We show that the different ground states arise from slight variations in the underlying surface potential, pictured here as the gate of a three-terminal device.
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Affiliation(s)
- I Fernández-Torrente
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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12
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Abstract
Magnetic and superconducting interactions couple electrons together to form complex states of matter. We show that, at the atomic scale, both types of interactions can coexist and compete to influence the ground state of a localized magnetic moment. Local spectroscopy at 4.5 kelvin shows that the spin-1 system formed by manganese-phthalocyanine (MnPc) adsorbed on Pb(111) can lie in two different magnetic ground states. These are determined by the balance between Kondo screening and superconducting pair-breaking interactions. Both ground states alternate at nanometer length scales to form a Moiré-like superstructure. The quantum phase transition connecting the two (singlet and doublet) ground states is thus tuned by small changes in the molecule-lead interaction.
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Affiliation(s)
- K J Franke
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
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13
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Henningsen N, Rurali R, Limbach C, Drost R, Pascual JI, Franke KJ. Site-Dependent Coordination Bonding in Self-Assembled Metal-Organic Networks. J Phys Chem Lett 2011; 2:55-61. [PMID: 26295521 DOI: 10.1021/jz1015907] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The combination of organic linkers with metal atoms on top of inorganic substrates offers promising perspectives for functional electronic and magnetic nanoscale devices. Typically, coordination bonds between electron-rich end groups and transition-metal atoms lead to the self-assembly of metal-organic nanostructures, whose shape and electronic and magnetic properties crucially depend on the type of ligand. Here, we report on the site-selective bonding properties of Co atoms to the dichotomic dicyanoazobenzene molecule with its carbonitrile and diazo N-based moieties as possible ligands. Using low-temperature scanning tunneling microscopy (STM) and spectroscopy measurements, we resolve the formation of self-assembled metal-organic motifs. Cobalt atoms exhibit a clear spectroscopic fingerprint dependent on the different coordination site, which is further used to map their position, otherwise not clearly visible in the topographic STM images. Density functional theory corroborates the observed bonding patterns and evidences their coordinative nature.
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Affiliation(s)
- N Henningsen
- †Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - R Rurali
- ‡Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra, 08193 Bellaterra (Barcelona), Spain
| | - C Limbach
- †Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - R Drost
- †Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - J I Pascual
- §Institut für Experimentalphysik and Center for Supramolecular Interactions (CSI Berlin), Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - K J Franke
- §Institut für Experimentalphysik and Center for Supramolecular Interactions (CSI Berlin), Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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14
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Wells JW, Dil JH, Meier F, Lobo-Checa J, Petrov VN, Osterwalder J, Ugeda MM, Fernandez-Torrente I, Pascual JI, Rienks EDL, Jensen MF, Hofmann P. Nondegenerate metallic States on Bi(114): a one-dimensional topological metal. Phys Rev Lett 2009; 102:096802. [PMID: 19392548 DOI: 10.1103/physrevlett.102.096802] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Indexed: 05/27/2023]
Abstract
The (114) surface of the semimetal Bi is found to support a quasi-one-dimensional, metallic surface state. As required by symmetry, the state is degenerate along the Gamma-Y line of the surface Brillouin zone with a highest binding energy of approximately 150 meV. In the Gamma-X direction the degeneracy is lifted by the strong spin-orbit splitting in Bi, as directly shown by spin-resolved photoemission. This results in a Fermi contour consisting of two closely separated, parallel lines of opposite spin direction. It is argued that similar states on related insulators would give rise to a one-dimensional quantum spin Hall effect.
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Affiliation(s)
- J W Wells
- Institute for Storage Ring Facilities (ISA) and Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, 8000 Aarhus C, Denmark
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15
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Fernández-Torrente I, Franke KJ, Pascual JI. Vibrational Kondo effect in pure organic charge-transfer assemblies. Phys Rev Lett 2008; 101:217203. [PMID: 19113448 DOI: 10.1103/physrevlett.101.217203] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Indexed: 05/27/2023]
Abstract
A Kondo resonance has been observed using a scanning tunneling microscope on a single molecular layer of a purely organic charge-transfer salt grown on a metal surface. Analysis of the Kondo anomaly reveals that the electron acceptor of the film possesses a spin-1/2 ground state due to the localization of an unpaired electron in the conjugated lowest unoccupied molecular orbital. Because of the pi character of this molecular state the unpaired electron is strongly coupled to molecular vibrations, leading to the split of the Kondo resonance in vibrational sidebands.
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Affiliation(s)
- I Fernández-Torrente
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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16
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Gonzalez-Lakunza N, Fernández-Torrente I, Franke KJ, Lorente N, Arnau A, Pascual JI. Formation of dispersive hybrid bands at an organic-metal interface. Phys Rev Lett 2008; 100:156805. [PMID: 18518142 DOI: 10.1103/physrevlett.100.156805] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Indexed: 05/26/2023]
Abstract
An electronic band with quasi-one-dimensional dispersion is found at the interface between a monolayer of a charge-transfer complex (TTF-TCNQ) and a Au(111) surface. Combined local spectroscopy and numerical calculations show that the band results from a complex mixing of metal and molecular states. The molecular layer folds the underlying metal states and mixes with them selectively, through the TTF component, giving rise to anisotropic hybrid bands. Our results suggest that, by tuning the components of such molecular layers, the dimensionality and dispersion of organic-metal interface states can be engineered.
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Affiliation(s)
- N Gonzalez-Lakunza
- Departamento de Física de Materiales, Facultad de Química, UPV/EHU, San Sebastián, Spain
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17
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Schulze G, Franke KJ, Gagliardi A, Romano G, Lin CS, Rosa AL, Niehaus TA, Frauenheim T, Di Carlo A, Pecchia A, Pascual JI. Resonant electron heating and molecular phonon cooling in single C60 junctions. Phys Rev Lett 2008; 100:136801. [PMID: 18517981 DOI: 10.1103/physrevlett.100.136801] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Indexed: 05/26/2023]
Abstract
We study heating and heat dissipation of a single C(60) molecule in the junction of a scanning tunneling microscope by measuring the electron current required to thermally decompose the fullerene cage. The power for decomposition varies with electron energy and reflects the molecular resonance structure. When the scanning tunneling microscope tip contacts the fullerene the molecule can sustain much larger currents. Transport simulations explain these effects by molecular heating due to resonant electron-phonon coupling and molecular cooling by vibrational decay into the tip upon contact formation.
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Affiliation(s)
- G Schulze
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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18
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Franke KJ, Schulze G, Henningsen N, Fernández-Torrente I, Pascual JI, Zarwell S, Rück-Braun K, Cobian M, Lorente N. Reducing the molecule-substrate coupling in C60-based nanostructures by molecular interactions. Phys Rev Lett 2008; 100:036807. [PMID: 18233024 DOI: 10.1103/physrevlett.100.036807] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Indexed: 05/25/2023]
Abstract
Codeposition of C60 and the three-dimensional molecular hydrocarbon 1,3,5,7-tetraphenyladamantane (TPA) on Au(111) leads to the spontaneous formation of molecular nanostructures in which each fullerene is locked into a specific orientation by three surrounding TPA. Scanning tunneling spectroscopy shows that the electronic coupling of C60 with the surface is significantly reduced in these nanostructures, enhancing the free-molecule properties. As evidenced by density functional theory simulations, the nanostructures are stabilized by 18 local electrostatic forces between C60 and TPA, resulting in a lifting of the C60 cage from the surface.
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Affiliation(s)
- K J Franke
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, Berlin, Germany.
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19
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Fernandez-Torrente I, Monturet S, Franke KJ, Fraxedas J, Lorente N, Pascual JI. Long-range repulsive interaction between molecules on a metal surface induced by charge transfer. Phys Rev Lett 2007; 99:176103. [PMID: 17995350 DOI: 10.1103/physrevlett.99.176103] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2007] [Indexed: 05/24/2023]
Abstract
The adsorption of a molecular electron donor on Au(111) is characterized by the spontaneous formation of a superlattice of monomers spaced several nanometers apart. The coverage-dependent molecular pair distributions obtained from scanning tunneling microscopy data reveal an intermolecular long-range repulsive potential, which decreases as the inverse of the molecular separation. Density functional theory calculations show a charge accumulation in the molecules due to electron donation into the metal. Our results suggest that electrostatic repulsion between molecules persists on the surface of a metal.
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Affiliation(s)
- I Fernandez-Torrente
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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20
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Fernandez-Torrente I, Franke KJ, Henningsen N, Schulze G, Alemani M, Roth C, Rurali R, Lorente N, Pascual JI. Spontaneous Formation of Triptycene Supramolecules on Surfaces. J Phys Chem B 2006; 110:20089-92. [PMID: 17034178 DOI: 10.1021/jp065149x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the limit of weak molecular interaction with an inorganic surface, noncovalent interactions between molecules dominate the nucleation and thin-film growth. Here, we report on the formation of three-dimensional triptycene clusters with a particularly stable structure. Once formed at the early stage of molecular adsorption, the clusters are stable for all temperatures until desorption. Furthermore, the clusters diffuse and nucleate as individual entities, therefore constituting building blocks for the later thin-film formation. High resolution scanning tunneling microscopy images indicate that the cluster is stabilized by C-H-pi interactions. The formation of such molecular structures at a surface is possible because the three-dimensional structure of the triptycene molecule leads to a very weak and mobile adsorption state. These results show that it is possible to investigate complex pathways in the formation of three-dimensional supramolecules at surfaces using a scanning tunneling microscope.
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21
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Pascual JI, Dick A, Hansmann M, Rust HP, Neugebauer J, Horn K. Bulk electronic structure of metals resolved with scanning tunneling microscopy. Phys Rev Lett 2006; 96:046801. [PMID: 16486866 DOI: 10.1103/physrevlett.96.046801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Indexed: 05/06/2023]
Abstract
We demonstrate that bulk band structure can have a strong influence in scanning tunneling microscopy measurements by resolving electronic interference patterns associated with scattering phenomena of bulk states at a metal surface and reconstructing the bulk band topology. Our data reveal that bulk information can be detected because states at the edge of the surface-projected bulk band have a predominant role on the scattering patterns. With the aid of density functional calculations, we associate this effect with an intrinsic increase in the projected density of states of edge states. This enhancement is characteristic of the three-dimensional bulk band curvature, a phenomenon analog to a van Hove singularity.
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Affiliation(s)
- J I Pascual
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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22
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Pascual JI, Grasa V, Cuesta JA. [Laparoscopic surgery in urology]. An Sist Sanit Navar 2005; 28 Suppl 3:109-16. [PMID: 16511585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
At the present time minimally invasive surgery is present in all the standards of quality of a surgical service. Laparoscopic surgery, the basis of this minimally invasive surgery, is revolutionizing the teaching and handling of many surgical pathologies. In the urological sphere, although with a delay of 5 years with respect to neighbouring countries, laparoscopy has become established as a prevalent technique in many processes of the urinary-genital apparatus. At present it is the chosen technique for the surgical treatment of the suprarenal, and it is rapidly becoming established in different pathologies such as renal tumours, prostate tumours, staging in neoplastic diseases of the testicles, benign surgical pathology and in reconstructive surgery. Since 1995, the Urology Service at the Hospital de Navarra has been a pioneer in the employment of this type of technique, and, since 1998, it has been a pioneer of so-called advanced laparoscopic surgery, in which it is a national reference point in some of the procedures, such as laparoscopic adrenalectomy. At present, all of the laparoscopic procedures are incorporated in the service, with a learning curve that has been surpassed. All of this has made it possible to improve patient care, to obtain a reduction in postoperative pain and in length of hospital stay, and a rapid return to labour activity with oncological results that can be equivalent on those of open surgery.
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Affiliation(s)
- J I Pascual
- Servicio de Urología, Hospital de Navarra, Pamplona.
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23
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Pascual JI, Bihlmayer G, Koroteev YM, Rust HP, Ceballos G, Hansmann M, Horn K, Chulkov EV, Blügel S, Echenique PM, Hofmann P. Role of spin in quasiparticle interference. Phys Rev Lett 2004; 93:196802. [PMID: 15600862 DOI: 10.1103/physrevlett.93.196802] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Indexed: 05/24/2023]
Abstract
Quasiparticle interference patterns measured by scanning tunneling microscopy can be used to study the local electronic structure of metal surfaces and high-temperature superconductors. Here, we show that even in nonmagnetic systems the spin of the quasiparticles can have a profound effect on the interference patterns. On Bi(110), where the surface state bands are not spin degenerate, the patterns are not related to the dispersion of the electronic states in a simple way. In fact, the features which are expected for the spin-independent situation are absent and the observed interference patterns can be interpreted only by taking spin-conserving scattering events into account.
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Affiliation(s)
- J I Pascual
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
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24
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Pascual JI, Barth JV, Ceballos G, Trimarchi G, De Vita A, Kern K, Rust HP. Mesoscopic chiral reshaping of the Ag(110) surface induced by the organic molecule PVBA. J Chem Phys 2004; 120:11367-70. [PMID: 15268168 DOI: 10.1063/1.1763836] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report scanning tunneling microscopy observations on the restructuring of a Ag(110) surface induced by the molecule 4-[trans-2-(pyrid-4-yl-vinyl)]benzoic acid (PVBA). Our data reveal that the surface undergoes a mesoscopic step faceting following exposure to submonolayer coverages and thermal activation. A sawtooth arrangement evolves implying long-range mass transport of substrate atoms and forming a regular arrangement of kink sites. Its formation is associated with the molecules' functional headgroups forming carboxylates with [100] Ag microfacets at step edges, and eventually operating to reshape the surface morphology. Interestingly, the resulting microfacets act as chiral templates for the growth of supramolecular PVBA structures. Theoretical modeling based on ab initio results indicates that chiral recognition processes discriminating between the two enantiomers of adsorbed PVBA molecules occur in this process.
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Affiliation(s)
- J I Pascual
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
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25
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Pascual JI, Lorente N, Song Z, Conrad H, Rust HP. Selectivity in vibrationally mediated single-molecule chemistry. Nature 2003; 423:525-8. [PMID: 12774118 DOI: 10.1038/nature01649] [Citation(s) in RCA: 300] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2002] [Accepted: 04/08/2003] [Indexed: 11/08/2022]
Abstract
The selective excitation of molecular vibrations provides a means to directly influence the speed and outcome of chemical reactions. Such mode-selective chemistry has traditionally used laser pulses to prepare reactants in specific vibrational states to enhance reactivity or modify the distribution of product species. Inelastic tunnelling electrons may also excite molecular vibrations and have been used to that effect on adsorbed molecules, to cleave individual chemical bonds and induce molecular motion or dissociation. Here we demonstrate that inelastic tunnelling electrons can be tuned to induce selectively either the translation or desorption of individual ammonia molecules on a Cu(100) surface. We are able to select a particular reaction pathway by adjusting the electronic tunnelling current and energy during the reaction induction such that we activate either the stretching vibration of ammonia or the inversion of its pyramidal structure. Our results illustrate the ability of the scanning tunnelling microscope to probe single-molecule events in the limit of very low yield and very low power irradiation, which should allow the investigation of reaction pathways not readily amenable to study by more conventional approaches.
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Affiliation(s)
- J I Pascual
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14194 Berlin, Germany.
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26
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Pascual JI, Gudiño-Cabrera G, Insausti R, Nieto-Sampedro M. Spinal implants of olfactory ensheathing cells promote axon regeneration and bladder activity after bilateral lumbosacral dorsal rhizotomy in the adult rat. J Urol 2002; 167:1522-6. [PMID: 11832781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
PURPOSE We performed spinal implantation of olfactory ensheathing cells to demonstrate dorsal root afferent regeneration as well as bladder activity restoration after lumbosacral L6 to S2 rhizotomy. MATERIALS AND METHODS Spinal segments receiving bladder innervation, usually L6, S1 and S2, were identified by bipolar stimulation of the ventral roots. Bilateral section of the identified dorsal roots L6 to S2 was performed in 18 male Wistar rats. Immediately after rhizotomy olfactory ensheathing cells or vehicle was unilaterally injected in the vicinity of the sacral parasympathetic nucleus in 9 rats each using a glass micropipette and air pulse system. The severed roots were reattached to the cord with fibrin glue and the animals recovered under antibiotic prophylaxis. RESULTS Anatomical regeneration of bladder wall primary afferents was demonstrated by the presence of labeled wheat germ agglutinin-horseradish peroxidase fibers in the dorsal horn and sacral parasympathetic nucleus in 8 of 9 cases of olfactory ensheathing cell implantation but not in the 9 controls injected with vehicle. One week after surgery all rats had an atonic bladder on cystometrography. At 6 weeks 8 of the 9 olfactory ensheathing cell implanted rats had recovered bladder activity. No recovery was observed in controls, in which vehicle was injected instead of olfactory ensheathing cells. CONCLUSIONS Regenerated primary afferent fibers from the bladder project to the sacral parasympathetic nucleus, where they presumably form synapses mediating the recovery of bladder activity. Thus, olfactory ensheathing cell implants in the adult rat promote sensory axon regeneration, target reinnervation and bladder activity restoration.
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Affiliation(s)
- J I Pascual
- Department of Urology and Neuromorphology Laboratory, Biomedical Research Unit, Hospital of Navarra, Pamplona, Spain
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27
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Pascual JI, Jackiw JJ, Song Z, Weiss PS, Conrad H, Rust HP. Adsorbate-substrate vibrational modes of benzene on Ag(110) resolved with scanning tunneling spectroscopy. Phys Rev Lett 2001; 86:1050-1053. [PMID: 11178007 DOI: 10.1103/physrevlett.86.1050] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2000] [Indexed: 05/23/2023]
Abstract
Using a low temperature scanning tunneling microscope, we have detected low energy adsorbate-substrate (external or frustrated) vibrational modes of benzene molecules adsorbed on a Ag(110) surface. We demonstrate that such vibrations represent a fingerprint of the molecules' chemical state and environment; two different vibrational spectra are measured on molecules populating two different adsorption states. We also find that the distortion of the adsorption geometry of the molecules may give rise to the excitation of additional (initially hidden) modes. Important differences in the spatial distribution of the inelastic signal are also observed for these external modes.
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Affiliation(s)
- J I Pascual
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany
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28
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Pascual JI, Gomez-Herrero J, Baro AM, Sanchez-Portal D, Artacho E, Ordejon P, Soler JM. Comment on "Identifying molecular orientation of individual C60 on a Si(111)-(7x7) Surface". Phys Rev Lett 2000; 85:2653. [PMID: 10978136 DOI: 10.1103/physrevlett.85.2653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/1999] [Indexed: 05/23/2023]
Affiliation(s)
- JI Pascual
- Fritz-Haber-Institut Faradayweg 4-6D-14195 Berlin, Germany
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29
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Pascual JI, Insausti R, Gonzalo LM. [Effects of selective vegetative denervation on the urinary bladder of the adult rat]. An Sist Sanit Navar 1997; 20:25-32. [PMID: 12891456 DOI: 10.23938/assn.0595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The present work is a study of the plastic capacity of the peripheral nervous system subjected to different aggressions in the case of 28 rats of the Wistar breed. They were divided into four groups: 1) sympathetic deafness (n=9); 2) parasympathetic deafness (n=9); 3) evaluation of regeneration (n=9); 4) control group (n=5). An image analyser was used to study the acetylcholinesterase (AChE) and Tyrosine Hydroxylase (TH) positive ganglionic neurones of the pelvic ganglion (GP) as well as the dorsal ganglions (GRD) compared with the control group. With group 3 a study was also made of the possible plasticity of the transacted axons using a wheat germ agglutinin conjugated-horseradish peroxidase (WGA-HRP) neurotracer. The statistical study was carried out by means of the analysis of variance (ANOVA), Fisher test and Scheffe method, with a p<0.05 taken as significant. The results show the predominant role of the pelvic nerve in the modulation of the plastic changes produced at the ganglionic level, with a lesser influence of the hypogastric nerve. Further studies are needed in order to define the specific role of each of these in the act of miction.
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Affiliation(s)
- J I Pascual
- Servicio de Urología, Hospital de Navarra, Pamplona
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30
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Pascual JI, Méndez J, Gómez-Herrero J, Baró AM, Garcia N, Landman U, Luedtke WD, Bogachek EN, Cheng HP. Properties of Metallic Nanowires: From Conductance Quantization to Localization. Science 1995; 267:1793-5. [PMID: 17775806 DOI: 10.1126/science.267.5205.1793] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Material structures of reduced dimensions exhibit electrical and mechanical properties different from those in the bulk. Measurements of room-temperature electronic transport in pulled metallic nanowires are presented, demonstrating that the conductance characteristics depend on the length, lateral dimensions, state and degree of disorder, and elongation mechanism of the wire. Conductance during the elongation of short wires (length l approximately 50 angstroms) exhibits periodic quantization steps with characteristic dips, correlating with the order-disorder states of layers of atoms in the wire predicted by molecular dynamics simulations. The resistance R of wires as long as l approximately 400 angstroms exhibits localization characteristics with In R(l) approximately l(2).
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31
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Torres JA, Pascual JI, Sáenz JJ. Theory of conduction through narrow constrictions in a three-dimensional electron gas. Phys Rev B Condens Matter 1994; 49:16581-16584. [PMID: 10010814 DOI: 10.1103/physrevb.49.16581] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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32
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33
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Pascual JI, Méndez J, Gómez-Herrero J, Baró AM, García N, Binh VT. Quantum contact in gold nanostructures by scanning tunneling microscopy. Phys Rev Lett 1993; 71:1852-1855. [PMID: 10054516 DOI: 10.1103/physrevlett.71.1852] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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34
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Pascual JI, Insausti R, Gonzalo LM. Urinary bladder innervation in male rat: termination of primary afferents in the spinal cord as determined by transganglionic transport of WGA-HRP. J Urol 1993; 150:500-4. [PMID: 7686986 DOI: 10.1016/s0022-5347(17)35535-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The distribution of afferents innervating the urinary bladder in the spinal cord of male rats has been studied with the axonal tracer horseradish peroxidase conjugated to wheat germ agglutinin (WGA-HRP) injected into various portions of one side of the urinary bladder (dome, body, base, or neck) and other pelvic organs (prostate and rectum). Labeled neurons were found in dorsal root ganglia of the lumbosacral cord (L1-S3, peak in S1-S2). The strongest and most extensive transganglionic labeling of primary afferents resulted after injections in the body of the bladder. Primary afferents were observed bilaterally in Lissauer's tract and laminae I-II at the apex of the dorsal horn, from L6 to S3. The projection extended laterally up to the sacral parasympathetic nucleus and medially up to the gray matter dorsal to the central canal, where they formed a plexus of fibers and terminals. Deposits in the dome and base of the bladder labeled more heavily the medial projection, while the least intense projection was seen after injections in the bladder neck. Our results indicate a common pattern of termination of primary afferents from the bladder, although some topographical differences exist.
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Affiliation(s)
- J I Pascual
- Department of Urology, Hospital of Navarra, Pamplona, Spain
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Pascual JI, Insausti R, Gonzalo LM. Pudendal nerve topography in the rat spinal cord projections studied with the axonal tracer wheat germ agglutinin conjugated-horseradish peroxidase. J Urol 1992; 147:718-22. [PMID: 1538470 DOI: 10.1016/s0022-5347(17)37365-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The spinal cord termination of the sensory fibers of the rat pudendal nerve has been determined by using the transganglionic transport of horseradish peroxidase conjugated to wheat germ agglutinin. The gross anatomical examination of the pudendal plexus indicated the existence of dorsal and ventral branches in the sensory division of the pudendal nerve. Either branch or both were sectioned and exposed to a 1% solution of the enzyme. After an average survival period of 48 hours, the resulting reaction product was studied both at the level of the dorsal root ganglia and the spinal cord. Labeled dorsal root ganglion cells were observed between L1 and S4 (peak in S1 and L6). Evidence of transganglionic transport of the tracer was observed from L5 to S2. The ventral branch projected medially in the superficial dorsal horn, while the dorsal branch projected laterally. Our findings are consistent with a segregation of sensibilities for the ventral and dorsal branches that convey urogenital (ventral branch) and anal (dorsal branch) cutaneous sensations at the level of termination of primary afferents.
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Affiliation(s)
- J I Pascual
- Department of Urology, Hospital of Navarra, Pamplona, Spain
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Porras V, Pascual JI, Mateos J, Almajano C. [Congenital bladder diverticulum as a cause of acute urinary retention]. ARCH ESP UROL 1990; 43:182-4. [PMID: 2114070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A case of acute urinary retention secondary to a giant bladder diverticulum in a 23-year-old patient is described. Its etiopathogenesis is briefly discussed, highlighting its congenital origin which, in our view, must be based on the histological examination of the specimen.
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Affiliation(s)
- V Porras
- Servicio de Urología, Hospital Real y Provincial Nuestra Señora de Gracia, Zaragoza, España
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Pascual JI, Porras V, Mateos J, Almajano C. [Bladder bilharziasis. Presentation of a clinical case]. Actas Urol Esp 1989; 13:271-2. [PMID: 2508439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We present a case of vesical Bilharziosis in a young black man. We briefly discuss the pathogeny, the diagnosis, based fundamentally on the microscopic study of urine and cystoscopy, as well as the treatment with Praziquantel as the preferential medication in Schistosomiasis due to S. haematobium.
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Abstract
WGA-HRP was applied to the pelvic and pudendal nerves of Sprague-Dawley and Wistar rats to compare the segmental levels of the resulting labeling. L6 and S1 were the segments at which the sacral parasympathetic nucleus and the denser primary afferents occurred in Sprague-Dawley rats. The levels found in Wistar rats were S1 and S2, thus indicating a disparity between both strains of rats in the spinal level of the sacral parasympathetic nucleus and the primary afferents.
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Affiliation(s)
- J I Pascual
- Division of Urology, Hospital Provincial of Zaragoza, Spain
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