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Grewal A, Leon CC, Kuhnke K, Kern K, Gunnarsson O. Scanning Tunneling Microscopy for Molecules: Effects of Electron Propagation into Vacuum. ACS NANO 2024; 18:12158-12167. [PMID: 38684019 PMCID: PMC11100283 DOI: 10.1021/acsnano.3c12315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 03/26/2024] [Accepted: 04/04/2024] [Indexed: 05/02/2024]
Abstract
Using scanning tunneling microscopy (STM), we experimentally and theoretically investigate isolated platinum phthalocyanine (PtPc) molecules adsorbed on an atomically thin NaCl(100) film vapor deposited on Au(111). We obtain good agreement between theory and constant-height STM topography. We theoretically examine why strong distortions of STM images occur as a function of distance between the molecule and the STM tip. The images of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) exhibit for increasing distance, significant radial expansion due to electron propagation in the vacuum. Additionally, the imaged angular dependence is substantially distorted. The LUMO image has substantial intensity along the molecular diagonals where PtPc has no atoms. In the electronic transport gap, the image differs drastically from HOMO and LUMO even at energies very close to these orbitals. As the tunneling becomes increasingly off-resonant, the eight angular lobes of the HOMO or of the degenerate LUMOs diminish and reveal four lobes with maxima along the molecular axes, where both, HOMO and LUMO have little or no weight. These images are strongly influenced by low-lying PtPc orbitals that have simple angular structures.
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Affiliation(s)
- Abhishek Grewal
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - Christopher C. Leon
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - Klaus Kuhnke
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - Klaus Kern
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
- Institut
de Physique, École Polytechnique
Fédérale de Lausanne, Lausanne 1015, Switzerland
| | - Olle Gunnarsson
- Max-Planck-Institut
für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
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2
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Sakanoue K, Fiorani A, Santo CI, Irkham, Valenti G, Paolucci F, Einaga Y. Boron-Doped Diamond Electrode Outperforms the State-of-the-Art Electrochemiluminescence from Microbeads Immunoassay. ACS Sens 2022; 7:1145-1155. [PMID: 35298151 DOI: 10.1021/acssensors.2c00156] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electrochemiluminescence (ECL) is a powerful transduction technique where light emission from a molecular species is triggered by an electrochemical reaction. Application to biosensors has led to a wide range of electroanalytical methods with particular impact on clinical analysis for diagnostic and therapeutic monitoring. Therefore, the quest for increasing the sensitivity while maintaining reproducible and easy procedures has brought investigations and innovations in (i) electrode materials, (ii) luminophores, and (iii) reagents. Particularly, the ECL signal is strongly affected by the electrode material and its surface modification during the ECL experiments. Here, we exploit boron-doped diamond (BDD) as an electrode material in microbead-based ECL immunoassay to be compared with the approach used in commercial instrumentation. We conducted a careful characterization of ECL signals from a tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)32+)/tri-n-propylamine (TPrA) system, both homogeneous (i.e., free diffusing Ru(bpy)32+) and heterogeneous (i.e., Ru(bpy)32+ bound on microbeads). We investigated the methods to promote TPrA oxidation, which led to the enhancement of ECL intensity, and the results revealed that the BDD surface properties greatly affect the ECL emission, so it does the addition of neutral, cationic, or anionic surfactants. Our results from homogeneous and heterogeneous microbead-based ECL show opposite outcomes, which have practical consequences in ECL optimization. In conclusion, by using Ru(bpy)32+-labeled immunoglobulins bound on microbeads, the ECL resulted in an increase of 70% and a double signal-to-noise ratio compared to platinum electrodes, which are actually used in commercial instrumentation for clinical analysis. This research infers that microbead-based ECL immunoassays with a higher sensitivity can be realized by BDD.
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Affiliation(s)
- Kohei Sakanoue
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
| | - Andrea Fiorani
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
| | - Claudio Ignazio Santo
- Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi 2, 40126, Bologna, Italy
| | - Irkham
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
| | - Giovanni Valenti
- Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi 2, 40126, Bologna, Italy
| | - Francesco Paolucci
- Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi 2, 40126, Bologna, Italy
| | - Yasuaki Einaga
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
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3
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Frolov AS, Sánchez-Barriga J, Callaert C, Hadermann J, Fedorov AV, Usachov DY, Chaika AN, Walls BC, Zhussupbekov K, Shvets IV, Muntwiler M, Amati M, Gregoratti L, Varykhalov AY, Rader O, Yashina LV. Atomic and Electronic Structure of a Multidomain GeTe Crystal. ACS NANO 2020; 14:16576-16589. [PMID: 33136362 DOI: 10.1021/acsnano.0c05851] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Renewed interest in the ferroelectric semiconductor germanium telluride was recently triggered by the direct observation of a giant Rashba effect and a 30-year-old dream about a functional spin field-effect transistor. In this respect, all-electrical control of the spin texture in this material in combination with ferroelectric properties at the nanoscale would create advanced functionalities in spintronics and data information processing. Here, we investigate the atomic and electronic properties of GeTe bulk single crystals and their (111) surfaces. We succeeded in growing crystals possessing solely inversion domains of ∼10 nm thickness parallel to each other. Using HAADF-TEM we observe two types of domain boundaries, one of them being similar in structure to the van der Waals gap in layered materials. This structure is responsible for the formation of surface domains with preferential Te-termination (∼68%) as we determined using photoelectron diffraction and XPS. The lateral dimensions of the surface domains are in the range of ∼10-100 nm, and both Ge- and Te-terminations reveal no reconstruction. Using spin-ARPES we establish an intrinsic quantitative relationship between the spin polarization of pure bulk states and the relative contribution of different terminations, a result that is consistent with a reversal of the spin texture of the bulk Rashba bands for opposite configurations of the ferroelectric polarization within individual nanodomains. Our findings are important for potential applications of ferroelectric Rashba semiconductors in nonvolatile spintronic devices with advanced memory and computing capabilities at the nanoscale.
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Affiliation(s)
- Alexander S Frolov
- Department of Chemistry, Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia
- Semenov Federal Research Center for Chemical Physics, Kosygina Street 4, 119991 Moscow, Russia
| | - Jaime Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Carolien Callaert
- EMAT, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Joke Hadermann
- EMAT, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Alexander V Fedorov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
- IFW Dresden, P.O. Box 270116, 01171 Dresden, Germany
- Joint Lab Functional Quantum Materials at BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Dmitry Yu Usachov
- St. Petersburg State University, 7/9 Universitetskaya nab., 199034 St. Petersburg, Russia
| | - Alexander N Chaika
- Institute of Solid State Physics RAS, Academician Ossipyan Street 2, Chernogolovka, 142432 Moscow District, Russia
| | - Brian C Walls
- CRANN, School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | | | - Igor V Shvets
- CRANN, School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - Matthias Muntwiler
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Matteo Amati
- Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Basovizza, Trieste, Italy
| | - Luca Gregoratti
- Elettra-Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Basovizza, Trieste, Italy
| | - Andrei Yu Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Oliver Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, Albert-Einstein-Straße 15, D-12489 Berlin, Germany
| | - Lada V Yashina
- Department of Chemistry, Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia
- Semenov Federal Research Center for Chemical Physics, Kosygina Street 4, 119991 Moscow, Russia
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4
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Grushko V, Beliuskina O, Mamalis A, Lysakovskiy V, Mitskevich E, Kiriev A, Petrosyan E, Chaplynskyi R, Bezshyyko O, Lysenko O. Energy conversion efficiency in betavoltaic cells based on the diamond Schottky diode with a thin drift layer. Appl Radiat Isot 2020; 157:109017. [PMID: 31889676 DOI: 10.1016/j.apradiso.2019.109017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 11/26/2019] [Accepted: 12/03/2019] [Indexed: 11/30/2022]
Abstract
The HPHT diamond Schottky diode was assembled as a Metal/Intrinsic/p-doped structure betavoltaic cell (BC) with a very thin (1 μm) drift layer and tested under 5-30 keV electron beam irradiation using a scanning electron microscope (SEM). The effect of the β-radiation energy and the backscattering of electrons on the energy conversion was studied. From the results obtained, it is shown that, the efficiency of the investigated BC increases from 1.01 to 3.75% with the decrease of β-particle energy from 30 to 5 keV due to an increase of the electron beam absorption in a thin drift layer. Maximum efficiency is achieved when the electron beam energy is close to the average β-decay energy of 3H. The BC maximum output power of the 1.6 μW was obtained at an electron beam energy of 15 keV, that matches the β-decay energy of 63Ni. The total BC conversion efficiency at 15 keV electron-beam energy is about 3%. The calculations indicated that a preferable β-source for the diamond based BCs with a thin (1 μm) drift layer is 63Ni.
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Affiliation(s)
- V Grushko
- V. Bakul Institute for Superhard Materials, 2, Avtozavodska, Kyiv, 04074, Ukraine
| | - O Beliuskina
- Department of Physics, University of Jyväskylä, Survontie 9, FI 40014, Finland.
| | - A Mamalis
- Project Center for Nanotechnology and Advanced Engineering (PC-NAE), NCSR "Demokritos", Athens, 15310, Greece
| | - V Lysakovskiy
- T. Shevchenko National University, 64/13, Volodymyrska, Kyiv, 01601, Ukraine
| | - E Mitskevich
- Institute for Nuclear Research, 47, Nauky Ave, Kyiv, 02000, Ukraine
| | - A Kiriev
- V. Bakul Institute for Superhard Materials, 2, Avtozavodska, Kyiv, 04074, Ukraine; T. Shevchenko National University, 64/13, Volodymyrska, Kyiv, 01601, Ukraine
| | - E Petrosyan
- Institute for Nuclear Research, 47, Nauky Ave, Kyiv, 02000, Ukraine
| | - R Chaplynskyi
- Institute for Nuclear Research, 47, Nauky Ave, Kyiv, 02000, Ukraine
| | - O Bezshyyko
- T. Shevchenko National University, 64/13, Volodymyrska, Kyiv, 01601, Ukraine
| | - O Lysenko
- V. Bakul Institute for Superhard Materials, 2, Avtozavodska, Kyiv, 04074, Ukraine
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5
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Yang N, Yu S, Macpherson JV, Einaga Y, Zhao H, Zhao G, Swain GM, Jiang X. Conductive diamond: synthesis, properties, and electrochemical applications. Chem Soc Rev 2019; 48:157-204. [DOI: 10.1039/c7cs00757d] [Citation(s) in RCA: 236] [Impact Index Per Article: 47.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This review summarizes systematically the growth, properties, and electrochemical applications of conductive diamond.
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Affiliation(s)
- Nianjun Yang
- Institute of Materials Engineering
- University of Siegen
- Siegen 57076
- Germany
| | - Siyu Yu
- Institute of Materials Engineering
- University of Siegen
- Siegen 57076
- Germany
| | | | - Yasuaki Einaga
- Department of Chemistry
- Keio University
- Yokohama 223-8522
- Japan
| | - Hongying Zhao
- School of Chemical Science and Engineering
- Tongji University
- Shanghai 200092
- China
| | - Guohua Zhao
- School of Chemical Science and Engineering
- Tongji University
- Shanghai 200092
- China
| | | | - Xin Jiang
- Institute of Materials Engineering
- University of Siegen
- Siegen 57076
- Germany
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6
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Barborini M, Sorella S, Rontani M, Corni S. Correlation Effects in Scanning Tunneling Microscopy Images of Molecules Revealed by Quantum Monte Carlo. J Chem Theory Comput 2016; 12:5339-5349. [PMID: 27709944 DOI: 10.1021/acs.jctc.6b00710] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Scanning tunneling microscopy (STM) and spectroscopy probe the local density of states of single molecules electrically insulated from the substrate. The experimental images, although usually interpreted in terms of single-particle molecular orbitals, are associated with quasiparticle wave functions dressed by the whole electron-electron interaction. Here we propose an ab initio approach based on quantum Monte Carlo to calculate the quasiparticle wave functions of molecules. Through the comparison between Monte Carlo wave functions and their uncorrelated Hartree-Fock counterparts we visualize the electronic correlation embedded in the simulated STM images, highlighting the many-body features that might be observed.
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Affiliation(s)
| | - Sandro Sorella
- Scuola Internazionale Superiore di Studi Avanzati (SISSA) and CNR-IOM Democritos National Simulation Center, via Bonomea 265, 34136 Trieste, Italy
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7
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González C, Abad E, Dappe YJ, Cuevas JC. Theoretical study of carbon-based tips for scanning tunnelling microscopy. NANOTECHNOLOGY 2016; 27:105201. [PMID: 26861537 DOI: 10.1088/0957-4484/27/10/105201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Motivated by recent experiments, we present here a detailed theoretical analysis of the use of carbon-based conductive tips in scanning tunnelling microscopy. In particular, we employ ab initio methods based on density functional theory to explore a graphitic, an amorphous carbon and two diamond-like tips for imaging with a scanning tunnelling microscope (STM), and we compare them with standard metallic tips made of gold and tungsten. We investigate the performance of these tips in terms of the corrugation of the STM images acquired when scanning a single graphene sheet. Moreover, we analyse the impact of the tip-sample distance and show that it plays a fundamental role in the resolution and symmetry of the STM images. We also explore in depth how the adsorption of single atoms and molecules in the tip apexes modifies the STM images and demonstrate that, in general, it leads to an improved image resolution. The ensemble of our results provides strong evidence that carbon-based tips can significantly improve the resolution of STM images, as compared to more standard metallic tips, which may open a new line of research in scanning tunnelling microscopy.
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Affiliation(s)
- C González
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay 91191 Gif-sur-Yvette Cedex, France. Departamento de electrónica y Tecnología de Computadores, Universidad de Granada, Fuente Nueva & CITIC, Aynadamar E-18071 Granada, Spain
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9
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Chaika AN, Molodtsova OV, Zakharov AA, Marchenko D, Sánchez-Barriga J, Varykhalov A, Babenkov SV, Portail M, Zielinski M, Murphy BE, Krasnikov SA, Lübben O, Shvets IV, Aristov VY. Rotated domain network in graphene on cubic-SiC(001). NANOTECHNOLOGY 2014; 25:135605. [PMID: 24594516 DOI: 10.1088/0957-4484/25/13/135605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The atomic structure of the cubic-SiC(001) surface during ultra-high vacuum graphene synthesis has been studied using scanning tunneling microscopy (STM) and low-energy electron diffraction. Atomically resolved STM studies prove the synthesis of a uniform, millimeter-scale graphene overlayer consisting of nanodomains rotated by ±13.5° relative to the left angle bracket 110 right angle bracket-directed boundaries. The preferential directions of the domain boundaries coincide with the directions of carbon atomic chains on the SiC(001)-c(2 × 2) reconstruction, fabricated prior to graphene synthesis. The presented data show the correlation between the atomic structures of the SiC(001)-c(2 × 2) surface and the graphene/SiC(001) rotated domain network and pave the way for optimizing large-area graphene synthesis on low-cost cubic-SiC(001)/Si(001) wafers.
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Affiliation(s)
- Alexander N Chaika
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow District, 2 Academician Ossipyan str., 142432, Russian Federation. Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), School of Physics, Trinity College Dublin, Dublin 2, Ireland
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