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Guandalini A, Senga R, Lin YC, Suenaga K, Ferretti A, Varsano D, Recchia A, Barone P, Mauri F, Pichler T, Kramberger C. Excitonic Effects in Energy-Loss Spectra of Freestanding Graphene. NANO LETTERS 2023; 23:11835-11841. [PMID: 38088831 DOI: 10.1021/acs.nanolett.3c03863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
In this work, we perform electron energy-loss spectroscopy (EELS) of freestanding graphene with high energy and momentum resolution to disentangle the quasielastic scattering from the excitation gap of Dirac electrons close to the optical limit. We show the importance of many-body effects on electronic excitations at finite transferred momentum by comparing measured EELS to ab initio calculations at increasing levels of theory. Quasi-particle corrections and excitonic effects are addressed within the GW approximation and the Bethe-Salpeter equation, respectively. Both effects are essential in the description of the EEL spectra to obtain a quantitative agreement with experiments, with the position, dispersion, and shape of both the excitation gap and the π plasmon being significantly affected by excitonic effects.
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Affiliation(s)
- Alberto Guandalini
- S3 Centre, Istituto Nanoscienze, CNR, Via Campi 213/a, 41125 Modena, Italy
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Ryosuke Senga
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Yung-Chang Lin
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Kazu Suenaga
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
- The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Osaka, Ibaraki 567-0047, Japan
| | - Andrea Ferretti
- S3 Centre, Istituto Nanoscienze, CNR, Via Campi 213/a, 41125 Modena, Italy
| | - Daniele Varsano
- S3 Centre, Istituto Nanoscienze, CNR, Via Campi 213/a, 41125 Modena, Italy
| | - Andrea Recchia
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Center for Life NanoScience, Istituto Italiano di Tecnologia, viale Regina Elena 291, 00161 Rome, Italy
| | - Paolo Barone
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- CNR-SPIN, Area della Ricerca di Tor Vergata, Via del Fosso del Cavaliere 100, I-00133 Rome, Italy
| | - Francesco Mauri
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Thomas Pichler
- University of Vienna, Faculty of Physics, Strudlhofgasse 4, A1090 Vienna, Austria
| | - Christian Kramberger
- University of Vienna, Faculty of Physics, Strudlhofgasse 4, A1090 Vienna, Austria
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2
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Yang G, Fan J, Gao SP. Momentum and thickness dependent excitonic and plasmonic properties of 2D h-BN and MoS 2 restored from supercell calculations. NANOSCALE ADVANCES 2023; 5:6990-6998. [PMID: 38059031 PMCID: PMC10697014 DOI: 10.1039/d3na00670k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 10/25/2023] [Indexed: 12/08/2023]
Abstract
The comprehension and manipulation of the propagation characteristics of elementary excitations, such as excitons and plasmons, play a crucial role in tailoring the optical properties of low-dimensional materials. To this end, investigations into the momentum (q) dispersions of excitons and plasmons in confined geometry are required fundamentally. Due to advancements in momentum-resolved spectroscopy techniques, research on the q-dependent excitons or plasmons in low-dimensional materials is beginning to emerge. However, previous simulations of low-dimensional systems are adversely affected by the artificial vacuum spacing employed in the supercell approximation. Furthermore, the significance of layer thickness in determining the excitonic and plasmonic characteristics of two-dimensional (2D) materials remains largely unexplored in the context of finite q. Therefore, an extensive investigation into the momentum and thickness dependent behaviours of both excitons and plasmons in 2D materials, which are free of the influence of vacuum spacing, is lacking at present. In this article, we develop a restoration procedure to eliminate the influence of vacuum spacing, and obtain a comprehensive picture of momentum and layer thickness dependent excitonic and plasmonic properties of 2D hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS2). Our restored simulations are not only found to be in excellent agreement with available experiments, but also elucidate the roles of momentum and layer thickness in the excitonic and plasmonic properties of 2D h-BN and MoS2. We further unveil the dimensionality effect on the dispersion characteristics of excitons and plasmons in h-BN and MoS2. Our contribution will hopefully promote the understanding of the elementary excitations propagating in low-dimensional materials and pave the way for next-generation nanophotonic and optoelectronic devices.
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Affiliation(s)
- Guang Yang
- Department of Materials Science, Fudan University Shanghai 200433 P. R. China
| | - Jiachen Fan
- Department of Materials Science, Fudan University Shanghai 200433 P. R. China
| | - Shang-Peng Gao
- Department of Materials Science, Fudan University Shanghai 200433 P. R. China
- Yiwu Research Institute of Fudan University Yiwu Zhejiang 322000 P. R. China
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3
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Do TN, Shih PH, Gumbs G. Magnetoplasmons in magic-angle twisted bilayer graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:455703. [PMID: 37531966 DOI: 10.1088/1361-648x/acecf1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/02/2023] [Indexed: 08/04/2023]
Abstract
The magic-angle twisted bilayer graphene (MATBLG) has been demonstrated to exhibit exotic physical properties due to the special flat bands. However, exploiting the engineering of such properties by external fields is still in it infancy. Here we show that MATBLG under an external magnetic field presents a distinctive magnetoplasmon dispersion, which can be significantly modified by transferred momentum and charge doping. Along a wide range of transferred momentum, there exist special pronounced single magnetoplasmon and horizontal single-particle excitation modes near charge neutrality. We provide an insightful discussion of such unique features based on the electronic excitation of Landau levels quantized from the flat bands and Landau damping. Additionally, charge doping leads to peculiar multiple strong-weight magnetoplasmons. These characteristics make MATBLG a favorable candidate for plasmonic devices and technology applications.
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Affiliation(s)
- Thi-Nga Do
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Po-Hsin Shih
- Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, NY 10065, United States of America
| | - Godfrey Gumbs
- Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, NY 10065, United States of America
- Donostia International Physics Center (DIPC), P de Manuel Lardizabal, 4, 20018 San Sebastian, Basque Country, Spain
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4
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Lingerfelt DB, Yoshimura A, Jakowski J, Ganesh P, Sumpter BG. Extracting Inelastic Scattering Cross Sections for Finite and Aperiodic Materials from Electronic Dynamics Simulations. J Chem Theory Comput 2022; 18:7093-7107. [PMID: 36375179 DOI: 10.1021/acs.jctc.2c00882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Explicit time-dependent electronic structure theory methods are increasingly prevalent in the areas of condensed matter physics and quantum chemistry, with the broad-band optical absorptivity of molecular and small condensed-phase systems nowadays routinely studied with such approaches. In this paper, it is demonstrated that electronic dynamics simulations can similarly be employed to study cross sections for the scattering-induced electronic excitations probed in nonresonant inelastic X-ray scattering and momentum-resolved electron energy loss spectroscopies. A method is put forth for evaluating the electronic dynamic structure factor, which involves the application of a momentum boost-type perturbation and transformation of the resulting reciprocal space density fluctuations into the frequency domain. Good agreement is first demonstrated between the dynamic structure factor extracted from these electronic dynamics simulations and the corresponding transition matrix elements from linear response theory. The method is then applied to some extended (quasi)one-dimensional systems, for which the wave vector becomes a good quantum number in the thermodynamic limit. Finally, the dispersion of many-body excitations in a series of hydrogen-terminated graphene flakes (and twisted bilayers thereof) is investigated to highlight the utility of the presented approach for capturing morphology-dependent effects in the inelastic scattering cross sections of nanostructured and/or noncrystalline materials.
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Affiliation(s)
- David B Lingerfelt
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Anthony Yoshimura
- Lawrence Livermore National Laboratory, Livermore, California94550, United States
| | - Jacek Jakowski
- Computing and Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Panchapakesan Ganesh
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
| | - Bobby G Sumpter
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee37831, United States
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5
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Wang X, Xu L. Band Structure and Quantum Transport of Bent Bilayer Graphene. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8664. [PMID: 36500159 PMCID: PMC9740608 DOI: 10.3390/ma15238664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/28/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
We investigate the band structures and transport properties of a zigzag-edged bent bilayer graphene nanoribbon under a uniform perpendicular magnetic field. Due to its unique geometry, the edge and interface states can be controlled by an electric field or local potential, and the conductance exhibits interesting quantized behavior. When Zeeman splitting is considered, the edge states are spin-filtered, and a weak quantum spin Hall (WQSH) phase appears. In the presence of an electric field or local potential, a WQSH-QH junction or WQSH-spin-unbalanced QSH junction can be achieved, respectively, while fully spin-polarized currents appear in the interface region. Zeeman splitting lifts the spin degeneracy, leading to a WQSH around zero energy with a quantized two-terminal conductance of 4e2/h, which is robust against weak nonmagnetic disorder. These results provide a way to manipulate the band structures and transport properties of the system using an electric field, local potential, and Zeeman splitting.
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Affiliation(s)
- Xue Wang
- Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830046, China
- Center for Theoretical Physics, School of Physical Science and Technology, Xinjiang University, Urumqi 830046, China
| | - Lei Xu
- Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830046, China
- Center for Theoretical Physics, School of Physical Science and Technology, Xinjiang University, Urumqi 830046, China
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6
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Pisarra M, Gomez CV, Sindona A. Massive and massless plasmons in germanene nanosheets. Sci Rep 2022; 12:18624. [PMID: 36329251 PMCID: PMC9633710 DOI: 10.1038/s41598-022-23058-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
Abstract
Atomically thin crystals may exhibit peculiar dispersive electronic states equivalent to free charged particles of ultralight to ultraheavy masses. A rare coexistence of linear and parabolic dispersions yields correlated charge density modes exploitable for nanometric light confinement. Here, we use a time-dependent density-functional approach, under several levels of increasing accuracy, from the random-phase approximation to the Bethe-Salpeter equation formalism, to assess the role of different synthesized germanene samples as platforms for these plasmon excitations. In particular, we establish that both freestanding and some supported germenene monolayers can sustain infrared massless modes, resolved into an out-of-phase (optical) and an in-phase (acoustic) component. We further indicate precise experimental geometries that naturally host infrared massive modes, involving two different families of parabolic charge carriers. We thus show that the interplay of the massless and massive plasmons can be finetuned by applied extrinsic conditions or geometry deformations, which constitutes the core mechanism of germanene-based optoelectronic and plasmonic applications.
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Affiliation(s)
- Michele Pisarra
- Gruppo Collegato di Cosenza, Sezione dei Laboratori Nazionali di Frascati (LNF), Istituto Nazionale di Fisica Nucleare (INFN), Cubo 31C, 87036, Rende, CS, Italy
| | - Cristian Vacacela Gomez
- Facultad de Ciencias, Escuela Superior Politécnica de Chimborazo (ESPOCH), Riobamba, 060155, Ecuador
| | - Antonello Sindona
- Gruppo Collegato di Cosenza, Sezione dei Laboratori Nazionali di Frascati (LNF), Istituto Nazionale di Fisica Nucleare (INFN), Cubo 31C, 87036, Rende, CS, Italy. .,Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, 87036, Rende, CS, Italy.
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7
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Sindona A, Vacacela Gomez C, Pisarra M. Dielectric screening versus geometry deformation in two-dimensional allotropes of silicon and germanium. Sci Rep 2022; 12:15107. [PMID: 36068278 PMCID: PMC9448770 DOI: 10.1038/s41598-022-19260-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 08/26/2022] [Indexed: 12/02/2022] Open
Abstract
The search for connections between electronic and structural features is a key factor in the synthesis of artificial materials for on-demand applications, with graphene and analogous elemental semimetals playing a distinguished role as building blocks of photonic and plasmonic systems. In particular, a diversity of arrangements and electronic-state dispersions is offered by currently synthesized two-dimensional allotropes of silicon and germanium, respectively known as silicene and germanene. These monolayers make the ideal playground to understand how their collective and single-particle electronic states, excited by electron or light beams, may be controlled by geometry rather than doping or gating. Here, we provide such a study using time-dependent density-functional theory, in the random-phase approximation, to identify the structural dependent properties of charge-density plasmon oscillations and optical absorption in flat to buckled silicene and germanene lattices. We further single out flat germanene as an unprecedented two-dimensional conductor, hosting Dirac cone fermions in parallel with metal-like charge carriers, which contribute to strong intraband plasmon modes and one-electron excitations in the far-infrared limit. Finally, we show how this atypical scenario can be tuned by external stress or strain.
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Affiliation(s)
- Antonello Sindona
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, 87036, Rende, CS, Italy. .,INFN, Sezione LNF, Gruppo Collegato di Cosenza, Via P. Bucci, Cubo 31C, 87036, Rende, CS, Italy.
| | - Cristian Vacacela Gomez
- Facultad de Ciencias, Escuela Superior Politécnica de Chimborazo (ESPOCH), 060155, Riobamba, Ecuador
| | - Michele Pisarra
- INFN, Sezione LNF, Gruppo Collegato di Cosenza, Via P. Bucci, Cubo 31C, 87036, Rende, CS, Italy
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8
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Hong J, Svendsen MK, Koshino M, Pichler T, Xu H, Suenaga K, Thygesen KS. Momentum-Dependent Oscillator Strength Crossover of Excitons and Plasmons in Two-Dimensional PtSe 2. ACS NANO 2022; 16:12328-12337. [PMID: 35913822 DOI: 10.1021/acsnano.2c03322] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The 1T-phase layered PtX2 chalcogenide has attracted widespread interest due to its thickness dependent metal-semiconductor transition driven by strong interlayer coupling. While the ground state properties of this paradigmatic material system have been widely explored, its fundamental excitation spectrum remains poorly understood. Here we combine first-principles calculations with momentum (q) resolved electron energy loss spectroscopy (q-EELS) to study the collective excitations in 1T-PtSe2 from the monolayer limit to the bulk. At finite momentum transfer, all the spectra are dominated by two distinct interband plasmons that disperse to higher energy with increasing q. Interestingly, the absence of long-range screening in the two-dimensional (2D) limit inhibits the formation of long wavelength plasmons. Consequently, in the small-q limit, excitations in monolayer PtSe2 are exclusively of excitonic nature, and the loss spectrum coincides with the optical spectrum. The qualitatively different momentum dependence of excitons and plasmons enables us to unambiguously disentangle their spectral fingerprints in the excited state spectrum of layered 1T-PtSe2. This will help to discern the charge carrier plasmon and locally map the optical conductivity and trace the layer-dependent semiconductor to metal transition in 1T-PtSe2 and other 2D materials.
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Affiliation(s)
- Jinhua Hong
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Mark Kamper Svendsen
- Computational Atomic-scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Masanori Koshino
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Thomas Pichler
- Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Vienna, Austria
| | - Hua Xu
- Key Laboratory of Applied Surface and Colloid Chemistry, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an 710119, P. R. China
| | - Kazu Suenaga
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
- The Institute of Scientific and Industrial Research (ISIR-SANKEN), Osaka University, Ibaraki 567-0047, Japan
| | - Kristian S Thygesen
- Computational Atomic-scale Materials Design (CAMD), Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
- Center for Nanostructured Graphene (CNG), Department of Physics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
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9
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Li D, Aubertin K, Onidas D, Nizard P, Félidj N, Gazeau F, Mangeney C, Luo Y. Recent advances in non-plasmonic surface-enhanced Raman spectroscopy nanostructures for biomedical applications. WILEY INTERDISCIPLINARY REVIEWS. NANOMEDICINE AND NANOBIOTECHNOLOGY 2022; 14:e1795. [PMID: 35362261 DOI: 10.1002/wnan.1795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/18/2022] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
Surface-enhanced Raman spectroscopy (SERS) is an emerging powerful vibrational technique offering unprecedented opportunities in biomedical science for the sensitive detection of biomarkers and the imaging and tracking of biological samples. Conventional SERS detection is based on the use of plasmonic substrates (e.g., Au and Ag nanostructures), which exhibit very high enhancement factors (EF = 1010 -1011 ) but suffers from serious limitations, including light-induced local heating effect due to ohmic loss and expensive price. These drawbacks may limit detection accuracy and large-scaled practical applications. In this review, we focus on alternative approaches based on plasmon-free SERS detection on low-cost nanostructures, such as carbons, oxides, chalcogenides, polymers, silicons, and so forth. The mechanism of non-plasmonic SERS detection has been attributed to interfacial charge transfer between the substrate and the adsorbed molecules, with no photothermal side-effects but usually less EF compared with plasmonic nanostructures. The strategies to improve Raman signal detection, through the tailoring of substrate composition, structure, and surface chemistry, is reviewed and discussed. The biomedical applications, for example, SERS cell characterization, biosensing, and bioimaging are also presented, highlighting the importance of substrate surface functionalization to achieve sensitive, accurate analysis, and excellent biocompatibility. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > Biosensing Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.
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Affiliation(s)
- Da Li
- LCBPT, CNRS UMR 8601, Université Paris Cité, 45, rue des Saints-Pères, Paris, France
| | - Kelly Aubertin
- MSC, CNRS UMR 7057, Université Paris Cité, 45, rue des Saints-Pères, Paris, France
| | - Delphine Onidas
- LCBPT, CNRS UMR 8601, Université Paris Cité, 45, rue des Saints-Pères, Paris, France
| | - Philippe Nizard
- LCBPT, CNRS UMR 8601, Université Paris Cité, 45, rue des Saints-Pères, Paris, France
| | - Nordin Félidj
- ITODYS, CNRS UMR 7086, Université Paris Cité, 15, rue Jean Antoine de Baïf, Paris, France
| | - Florence Gazeau
- MSC, CNRS UMR 7057, Université Paris Cité, 45, rue des Saints-Pères, Paris, France
| | - Claire Mangeney
- LCBPT, CNRS UMR 8601, Université Paris Cité, 45, rue des Saints-Pères, Paris, France
| | - Yun Luo
- LCBPT, CNRS UMR 8601, Université Paris Cité, 45, rue des Saints-Pères, Paris, France
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Shu X, Lin J, Zhang H. Monolayered H-Si-P semiconductors: structural stability, electronic structure, optical properties, and prospects for photocatalytic water splitting. Phys Chem Chem Phys 2021; 23:13594-13602. [PMID: 34114581 DOI: 10.1039/d1cp01219c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Group IV and V monolayers are promising state-of-the-art two-dimensional (2D) materials owing to their high carrier mobility, tunable bandgaps, and optical linear dichroism along with outstanding electronic and thermoelectric properties. Furthermore, recent studies revealed the stability of free-standing 2D monolayers by hydrogenation. Inspired by this, we systematically predicted and investigated the structure and properties of various hydrogen-saturated silicon phosphide (H-Si-P) monolayers based on first-principles calculations. According to the results, H-Si-P monolayers belong to indirect bandgap semiconductors with a highly stable structure. Their bandgaps and band edge positions assessed using accurate hybrid functional are shown to be effectively adjusted by applying a biaxial strain. Furthermore, the absorption spectra of these monolayers, simulated in the context of time-dependent density functional theory, exhibit their excellent potential for solar energy conversion and visible-light-driven photocatalytic water splitting. In this respect, this work provides valuable guidance for finding more 2D semiconductors and nanostructures for nanoelectronics and optoelectronic applications, as well as for photocatalytic water splitting.
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Affiliation(s)
- Xiaoqin Shu
- School of Mathematics and Physics, Leshan Normal College, Leshan, 614000, China
| | - Jiahe Lin
- School of Science, Jimei University, Fujian, 361021, China
| | - Hong Zhang
- College of Physical Science and Technology, Sichuan University, Chengdu, 610065, China.
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11
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Hong J, Senga R, Pichler T, Suenaga K. Probing Exciton Dispersions of Freestanding Monolayer WSe_{2} by Momentum-Resolved Electron Energy-Loss Spectroscopy. PHYSICAL REVIEW LETTERS 2020; 124:087401. [PMID: 32167311 DOI: 10.1103/physrevlett.124.087401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
Excitons, as bound electron-hole paired quasiparticle, play an essential role in the energy transport in the optical-electric properties of semiconductors. Their momentum-energy dispersion relation is a fundamental physical property of great significance to understand exciton dynamics. However, this dispersion is seldom explored especially in two-dimensional transition metal dichalcogenides with rich valleytronic properties. In this work, momentum resolved electron energy-loss spectroscopy was used to measure the dispersions of excitons in freestanding monolayer WSe_{2}. Besides the parabolically dispersed valley excitons, a subgap dispersive exciton was observed at nonzero momenta for the first time, which can be introduced by the prolific Se vacancies. Our work provides a paradigm to directly probe exciton dispersions in 2D semiconductors and could be generalized to many low-dimensional systems.
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Affiliation(s)
- Jinhua Hong
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Ryosuke Senga
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Thomas Pichler
- Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Vienna, Austria
| | - Kazu Suenaga
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
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12
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Gaufrès E, Fossard F, Gosselin V, Sponza L, Ducastelle F, Li Z, Louie SG, Martel R, Côté M, Loiseau A. Momentum-Resolved Dielectric Response of Free-Standing Mono-, Bi-, and Trilayer Black Phosphorus. NANO LETTERS 2019; 19:8303-8310. [PMID: 31603690 DOI: 10.1021/acs.nanolett.9b03928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Black phosphorus (BP), a 2D semiconducting material of interest in electronics and photonics, exhibits physical properties characterized by strong anisotropy and band gap energy that scales with reducing layer number. However, the investigation of its intrinsic properties is challenging because thin-layer BP is photo-oxidized under ambient conditions and the energy of its electronic states shifts in different dielectric environments. We prepared free-standing samples of few-layer BP under glovebox conditions and probed the dielectric response in a vacuum using scanning transmission electron microscopy and electron energy loss spectroscopy (STEM-EELS). Thresholds of the excitation energy are measured at 1.9, 1.4, and 1.1 eV for the mono-, bi-, and trilayer BP, respectively, and these values are used to estimate the corresponding optical band gaps. A comparison of our results with electronic structure calculations indicates that the variation of the quasi-particle gap is larger than that of the exciton binding energy. The dispersion of the plasmons versus momentum for one- to three-layer BP and bulk BP highlights a deviation from parabolic to linear dispersion and strong anisotropic fingerprints.
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Affiliation(s)
- Etienne Gaufrès
- Laboratoire d'Etude des Microstructures , ONERA-CNRS , UMR104, Université Paris-Saclay, BP 72, 92322 Châtillon Cedex , France
- LP2N, Laboratoire Photonique Numerique et Nanosciences , Univ. Bordeaux , F-33400 Talence , France
- Institut d'Optique & CNRS , UMR 5298, F-33400 Talence , France
| | - Frédéric Fossard
- Laboratoire d'Etude des Microstructures , ONERA-CNRS , UMR104, Université Paris-Saclay, BP 72, 92322 Châtillon Cedex , France
| | - Vincent Gosselin
- Département de Physique , Université de Montréal , Montréal QC H3C 3J7 , Canada
| | - Lorenzo Sponza
- Laboratoire d'Etude des Microstructures , ONERA-CNRS , UMR104, Université Paris-Saclay, BP 72, 92322 Châtillon Cedex , France
| | - François Ducastelle
- Laboratoire d'Etude des Microstructures , ONERA-CNRS , UMR104, Université Paris-Saclay, BP 72, 92322 Châtillon Cedex , France
| | - Zhenglu Li
- Department of Physics , University of California at Berkeley , Berkeley , California 94720 , United States
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Steven G Louie
- Department of Physics , University of California at Berkeley , Berkeley , California 94720 , United States
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Richard Martel
- Département de Chimie , Université de Montréal , Montréal QC H3C 3J7 , Canada
| | - Michel Côté
- Département de Physique , Université de Montréal , Montréal QC H3C 3J7 , Canada
| | - Annick Loiseau
- Laboratoire d'Etude des Microstructures , ONERA-CNRS , UMR104, Université Paris-Saclay, BP 72, 92322 Châtillon Cedex , France
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13
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Silkin VM, Chulkov EV, Echenique PM. Collective electronic excitations on the MgB2(0001) surfaces. ADVANCES IN QUANTUM CHEMISTRY 2019. [DOI: 10.1016/bs.aiq.2019.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Naumann M, Knupfer M. Complex momentum behavior of electronic excitations in β-CuPc. J Chem Phys 2018; 149:084704. [PMID: 30193487 DOI: 10.1063/1.5046388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The electronic excitation spectrum of β-CuPc has been investigated using electron energy-loss spectroscopy in transmission. Our results demonstrate a rather strong momentum dependence of the lowest exciton features. Both main components show a negative dispersion, and the momentum dependence indicates that this negative dispersion is parallel to the molecular stacks in β-CuPc. In addition, the spectral shape also varies upon increasing momentum transfer indicating a particular momentum dependence of the inter-molecular interactions.
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Affiliation(s)
- Marco Naumann
- IFW Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany
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15
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Senga R, Pichler T, Yomogida Y, Tanaka T, Kataura H, Suenaga K. Direct Proof of a Defect-Modulated Gap Transition in Semiconducting Nanotubes. NANO LETTERS 2018; 18:3920-3925. [PMID: 29783838 DOI: 10.1021/acs.nanolett.8b01284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Measurements of optical properties at a nanometer level are of central importance for the characterization of optoelectronic devices. It is, however, difficult to use conventional light-probe measurements to determine the local optical properties from a single quantum object with nanometrical inhomogeneity. Here, we successfully measured the optical gap transitions of an individual semiconducting carbon nanotube with defects by using a monochromated electron source as a probe. The optical conductivity extracted from an electron energy-loss spectrum for a certain type of defect presents a characteristic modification near the lowest excitation peak ( E11), where excitons and nonradiative transitions, as well as phonon-coupled excitations, are strongly involved. Detailed line-shape analysis of the E11 peak clearly shows different degrees of exciton lifetime shortening and electronic state modification according to the defect type.
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Affiliation(s)
- Ryosuke Senga
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565 , Japan
| | - Thomas Pichler
- Faculty of Physics , University of Vienna , Strudlhofgasse 4 , A-1090 Vienna , Austria
| | - Yohei Yomogida
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565 , Japan
| | - Takeshi Tanaka
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565 , Japan
| | - Hiromichi Kataura
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565 , Japan
| | - Kazu Suenaga
- Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565 , Japan
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16
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Hage FS, Hardcastle TP, Gjerding MN, Kepaptsoglou DM, Seabourne CR, Winther KT, Zan R, Amani JA, Hofsaess HC, Bangert U, Thygesen KS, Ramasse QM. Local Plasmon Engineering in Doped Graphene. ACS NANO 2018; 12:1837-1848. [PMID: 29369611 DOI: 10.1021/acsnano.7b08650] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Single-atom B or N substitutional doping in single-layer suspended graphene, realized by low-energy ion implantation, is shown to induce a dampening or enhancement of the characteristic interband π plasmon of graphene through a high-resolution electron energy loss spectroscopy study using scanning transmission electron microscopy. A relative 16% decrease or 20% increase in the π plasmon quality factor is attributed to the presence of a single substitutional B or N atom dopant, respectively. This modification is in both cases shown to be relatively localized, with data suggesting the plasmonic response tailoring can no longer be detected within experimental uncertainties beyond a distance of approximately 1 nm from the dopant. Ab initio calculations confirm the trends observed experimentally. Our results directly confirm the possibility of tailoring the plasmonic properties of graphene in the ultraviolet waveband at the atomic scale, a crucial step in the quest for utilizing graphene's properties toward the development of plasmonic and optoelectronic devices operating at ultraviolet frequencies.
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Affiliation(s)
| | - Trevor P Hardcastle
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K
- School of Chemical and Process Engineering, University of Leeds , Leeds LS2 9JT, U.K
| | - Morten N Gjerding
- CAMD and Center for Nanostructured Graphene (CNG), Technical University of Denmark , Fysikvej 1, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Demie M Kepaptsoglou
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K
- York NanoCentre, University of York , Heslington, York YO10 5BR, U.K
| | - Che R Seabourne
- School of Chemical and Process Engineering, University of Leeds , Leeds LS2 9JT, U.K
| | - Kirsten T Winther
- CAMD and Center for Nanostructured Graphene (CNG), Technical University of Denmark , Fysikvej 1, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Recep Zan
- Nanotechnology Application and Research Center, Niğde Omer Halisdemir University , Niğde 51000, Turkey
| | - Julian Alexander Amani
- II Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Hans C Hofsaess
- II Physikalisches Institut, Georg-August-Universität Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Ursel Bangert
- Bernal Institute and Department of Physics, University of Limerick , Limerick, Ireland
| | - Kristian S Thygesen
- CAMD and Center for Nanostructured Graphene (CNG), Technical University of Denmark , Fysikvej 1, Building 307, 2800 Kgs. Lyngby, Denmark
| | - Quentin M Ramasse
- SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, U.K
- School of Chemical and Process Engineering, University of Leeds , Leeds LS2 9JT, U.K
- School of Physics, University of Leeds , Leeds LS2 9JT, U.K
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17
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18
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Torbatian Z, Asgari R. Plasmon modes of bilayer molybdenum disulfide: a density functional study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:465701. [PMID: 28816178 DOI: 10.1088/1361-648x/aa86b9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We explore the collective electronic excitations of bilayer molybdenum disulfide (MoS2) using density functional theory together with random phase approximation. The many-body dielectric function and electron energy-loss spectra are calculated using an ab initio based model involving material-realistic physical properties. The electron energy-loss function of the bilayer MoS2 system is found to be sensitive to either electron or hole doping and this is due to the fact that the Kohn-Sham band dispersions are not symmetric for energies above and below the zero Fermi level. Three plasmon modes are predicted, a damped high-energy mode, one optical mode (in-phase mode) for which the plasmon dispersion exhibits [Formula: see text] in the long wavelength limit originating from low-energy electron scattering and finally a highly damped acoustic mode (out-of-phase mode).
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Affiliation(s)
- Z Torbatian
- School of Nano Science, Institute for Research in Fundamental Sciences (IPM), Tehran 19395-5531, Iran
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19
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Zheng H, Gan Y, Abbamonte P, Wagner LK. Importance of σ Bonding Electrons for the Accurate Description of Electron Correlation in Graphene. PHYSICAL REVIEW LETTERS 2017; 119:166402. [PMID: 29099202 DOI: 10.1103/physrevlett.119.166402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Indexed: 06/07/2023]
Abstract
Electron correlation in graphene is unique because of the interplay between the Dirac cone dispersion of π electrons and long-range Coulomb interaction. Because of the zero density of states at Fermi level, the random phase approximation predicts no metallic screening at long distance and low energy, so one might expect that graphene should be a poorly screened system. However, empirically graphene is a weakly interacting semimetal, which leads to the question of how electron correlations take place in graphene at different length scales. We address this question by computing the equal time and dynamic structure factor S(q) and S(q,ω) of freestanding graphene using ab initio fixed-node diffusion Monte Carlo simulations and the random phase approximation. We find that the σ electrons contribute strongly to S(q,ω) for relevant experimental values of ω even at distances up to around 80 Å. These findings illustrate how the emergent physics from underlying Coulomb interactions results in the observed weakly correlated semimetal.
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Affiliation(s)
- Huihuo Zheng
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Yu Gan
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Peter Abbamonte
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Lucas K Wagner
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
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20
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Aggoune W, Cocchi C, Nabok D, Rezouali K, Akli Belkhir M, Draxl C. Enhanced Light-Matter Interaction in Graphene/h-BN van der Waals Heterostructures. J Phys Chem Lett 2017; 8:1464-1471. [PMID: 28296404 DOI: 10.1021/acs.jpclett.7b00357] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
By investigating the optoelectronic properties of prototypical graphene/hexagonal boron nitride (h-BN) heterostructures, we demonstrate how a nanostructured combination of these materials can lead to a dramatic enhancement of light-matter interaction and give rise to unique excitations. In the framework of ab initio many-body perturbation theory, we show that such heterostructures absorb light over a broad frequency range, from the near-infrared to the ultraviolet (UV), and that each spectral region is characterized by a specific type of excitations. Delocalized electron-hole pairs in graphene dominate the low-energy part of the spectrum, while strongly bound electron-hole pairs in h-BN are preserved in the near-UV. Besides these features, characteristic of the pristine constituents, charge-transfer excitations appear across the visible region. Remarkably, the spatial distribution of the electron and the hole can be selectively tuned by modulating the stacking arrangement of the individual building blocks. Our results open up unprecedented perspectives in view of designing van der Waals heterostructures with tailored optoelectronic features.
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Affiliation(s)
- Wahib Aggoune
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
- Laboratoire de Physique Théorique, Faculté des Science Exactes, Université de Bejaia , 06000 Bejaia, Algeria
| | - Caterina Cocchi
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
| | - Dmitrii Nabok
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
| | - Karim Rezouali
- Laboratoire de Physique Théorique, Faculté des Science Exactes, Université de Bejaia , 06000 Bejaia, Algeria
| | - Mohamed Akli Belkhir
- Laboratoire de Physique Théorique, Faculté des Science Exactes, Université de Bejaia , 06000 Bejaia, Algeria
| | - Claudia Draxl
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin , 12489 Berlin, Germany
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21
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Vacacela Gomez C, Pisarra M, Gravina M, Sindona A. Tunable plasmons in regular planar arrays of graphene nanoribbons with armchair and zigzag-shaped edges. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2017; 8:172-182. [PMID: 28243554 PMCID: PMC5301920 DOI: 10.3762/bjnano.8.18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 01/03/2017] [Indexed: 06/02/2023]
Abstract
Recent experimental evidence for and the theoretical confirmation of tunable edge plasmons and surface plasmons in graphene nanoribbons have opened up new opportunities to scrutinize the main geometric and conformation factors, which can be used to modulate these collective modes in the infrared-to-terahertz frequency band. Here, we show how the extrinsic plasmon structure of regular planar arrays of graphene nanoribbons, with perfectly symmetric edges, is influenced by the width, chirality and unit-cell length of each ribbon, as well as the in-plane vacuum distance between two contiguous ribbons. Our predictions, based on time-dependent density functional theory, in the random phase approximation, are expected to be of immediate help for measurements of plasmonic features in nanoscale architectures of nanoribbon devices.
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Affiliation(s)
- Cristian Vacacela Gomez
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, 87036 Rende (CS), Italy
- INFN, sezione LNF, Gruppo collegato di Cosenza, Via P. Bucci, Cubo 31C, 87036 Rende (CS), Italy
| | - Michele Pisarra
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, 87036 Rende (CS), Italy
- Departamento de Química, Universidad Autónoma de Madrid, Calle Francisco Tomás y Valiente 7 (Módulo 13), 28049, Madrid, Spain
| | - Mario Gravina
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, 87036 Rende (CS), Italy
- INFN, sezione LNF, Gruppo collegato di Cosenza, Via P. Bucci, Cubo 31C, 87036 Rende (CS), Italy
| | - Antonello Sindona
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, 87036 Rende (CS), Italy
- INFN, sezione LNF, Gruppo collegato di Cosenza, Via P. Bucci, Cubo 31C, 87036 Rende (CS), Italy
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22
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Shih PH, Chiu YH, Wu JY, Shyu FL, Lin MF. Coulomb excitations of monolayer germanene. Sci Rep 2017; 7:40600. [PMID: 28091555 PMCID: PMC5238379 DOI: 10.1038/srep40600] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 12/07/2016] [Indexed: 01/29/2023] Open
Abstract
The feature-rich electronic excitations of monolayer germanene lie in the significant spin-orbit coupling and the buckled structure. The collective and single-particle excitations are diversified by the magnitude and direction of transferred momentum, the Fermi energy and the gate voltage. There are four kinds of plasmon modes, according to the unique frequency- and momentum-dependent phase diagrams. They behave as two-dimensional acoustic modes at long wavelength. However, for the larger momenta, they might change into another kind of undamped plasmons, become the seriously suppressed modes in the heavy intraband e-h excitations, keep the same undamped plasmons, or decline and then vanish in the strong interband e-h excitations. Germanene, silicene and graphene are quite different from one another in the main features of the diverse plasmon modes.
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Affiliation(s)
- Po-Hsin Shih
- Department of Physics, National Cheng Kung University, Taiwan
| | - Yu-Huang Chiu
- Department of Applied Physics, National Pingtung University, Pingtung, Taiwan
| | - Jhao-Ying Wu
- Center for General Education, National Kaohsiung Marine University, Kaohsiung, Taiwan
| | - Feng-Lin Shyu
- Department of Physics, Republic of China Military Academy, Kaohsiung, Taiwan
| | - Ming-Fa Lin
- Department of Physics, National Cheng Kung University, Taiwan
- National Center for Theoretical Sciences (south), Taiwan
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23
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Vacacela Gomez C, Pisarra M, Gravina M, Pitarke JM, Sindona A. Plasmon Modes of Graphene Nanoribbons with Periodic Planar Arrangements. PHYSICAL REVIEW LETTERS 2016; 117:116801. [PMID: 27661709 DOI: 10.1103/physrevlett.117.116801] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Indexed: 06/06/2023]
Abstract
Among their amazing properties, graphene and related low-dimensional materials show quantized charge-density fluctuations-known as plasmons-when exposed to photons or electrons of suitable energies. Graphene nanoribbons offer an enhanced tunability of these resonant modes, due to their geometrically controllable band gaps. The formidable effort made over recent years in developing graphene-based technologies is however weakened by a lack of predictive modeling approaches that draw upon available ab initio methods. An example of such a framework is presented here, focusing on narrow-width graphene nanoribbons, organized in periodic planar arrays. Time-dependent density-functional calculations reveal unprecedented plasmon modes of different nature at visible to infrared energies. Specifically, semimetallic (zigzag) nanoribbons display an intraband plasmon following the energy-momentum dispersion of a two-dimensional electron gas. Semiconducting (armchair) nanoribbons are instead characterized by two distinct intraband and interband plasmons, whose fascinating interplay is extremely responsive to either injection of charge carriers or increase in electronic temperature. These oscillations share some common trends with recent nanoinfrared imaging of confined edge and surface plasmon modes detected in graphene nanoribbons of 100-500 nm width.
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Affiliation(s)
- C Vacacela Gomez
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, I-87036 Rende (CS), Italy
- INFN, Sezione LNF, Gruppo Collegato di Cosenza, Cubo 31C, I-87036 Rende (CS), Italy
| | - M Pisarra
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, I-87036 Rende (CS), Italy
- Departamento de Química, Universidad Autónoma de Madrid, Calle Francisco Tomás y Valiente 7 (Módulo 13), E-28049 Madrid, Spain
| | - M Gravina
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, I-87036 Rende (CS), Italy
- INFN, Sezione LNF, Gruppo Collegato di Cosenza, Cubo 31C, I-87036 Rende (CS), Italy
| | - J M Pitarke
- CIC nanoGUNE, Tolosa Hiribidea 76, E-20018 Donostia-San Sebastian, Basque Country, Spain
- Materia Kondentsatuaren Fisika Saila, DIPC, and Centro Fisica Materiales CSIC-UPV/EHU, 644 Posta Kutxatila, E-48080 Bilbo, Basque Country, Spain
| | - A Sindona
- Dipartimento di Fisica, Università della Calabria, Via P. Bucci, Cubo 30C, I-87036 Rende (CS), Italy
- INFN, Sezione LNF, Gruppo Collegato di Cosenza, Cubo 31C, I-87036 Rende (CS), Italy
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24
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Cheung W, Patel M, Ma Y, Chen Y, Xie Q, Lockard JV, Gao Y, He H. π-Plasmon absorption of carbon nanotubes for the selective and sensitive detection of Fe 3+ ions. Chem Sci 2016; 7:5192-5199. [PMID: 30155169 PMCID: PMC6020252 DOI: 10.1039/c6sc00006a] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 04/17/2016] [Indexed: 01/14/2023] Open
Abstract
Inspired by the remarkable electronic and optical properties of single walled carbon nanotubes (SWNTs), various molecular sensing devices with sensitivity down to the single molecule level have been developed. However, most sensing approaches such as field effect transistors or near infrared (NIR) fluorescence require the rigorous debundling and separation of metallic tubes and semiconducting tubes in order to reach the desired high sensitivity. Interestingly, all carbon nanomaterials including carbon nanotubes, graphite, graphene, and even amorphous carbon exhibit extremely strong π-plasmon absorption in the ultraviolet region. This strong absorption has been studied as an undesired optical background for applications based on visible and NIR absorptions. For the first time, we found that the strong π-plasmon absorption of SWNTs in the ultraviolet region is extremely sensitive to ion binding. It is even much more sensitive than the absorption in the visible and NIR regions. Herein, we present our first exploration into using the extremely strong plasmon absorption of SWNTs to develop a new sensing platform for the detection of metallic ions. The detection selectivity is realized by modifying the surface of SWNTs with molecular ligands that have a high specificity for metal ions. As a demonstration, the new method is applied to selectively detect iron ions (Fe3+) by modifying the surface of the SWNTs with deferoxamine (DFO), a natural bacterial siderophore, which has a high specificity and affinity for Fe3+. The selective detection of Fe3+ in both aqueous solution and complex rain water is achieved with a pM level of sensitivity and detection limit. In situ resonant Raman spectroscopy demonstrated that the sensitive detection possibly involves electron transfer between the formed Fe-DFO complexes and the SWNTs. We envisage that it can be used to detect other metal ions when a specific binding chelator is attached to the carbon nanotube surface.
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Affiliation(s)
- William Cheung
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , USA . ; ; Tel: +1-973-353-1254
| | - Mehulkumar Patel
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , USA . ; ; Tel: +1-973-353-1254
| | - Yufeng Ma
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , USA . ; ; Tel: +1-973-353-1254
| | - Yuan Chen
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , USA . ; ; Tel: +1-973-353-1254
| | - Qiaoqiao Xie
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , USA . ; ; Tel: +1-973-353-1254
| | - Jenny V Lockard
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , USA . ; ; Tel: +1-973-353-1254
| | - Yuan Gao
- Department of Earth & Environmental Sciences , Rutgers University , 101 Warren Street , Newark , New Jersey 07102 , USA
| | - Huixin He
- Department of Chemistry , Rutgers University , 73 Warren Street , Newark , New Jersey 07102 , USA . ; ; Tel: +1-973-353-1254
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25
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Senga R, Pichler T, Suenaga K. Electron Spectroscopy of Single Quantum Objects To Directly Correlate the Local Structure to Their Electronic Transport and Optical Properties. NANO LETTERS 2016; 16:3661-3667. [PMID: 27171894 DOI: 10.1021/acs.nanolett.6b00825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Physical property of a single quantum object is governed by its precise atomic arrangement. The direct correlation of localized physical properties with the atomic structures has been therefore strongly desired but still limited in the theoretical studies. Here, we have successfully examined the localized electronic properties of individual carbon nanotubes by means of high-resolution electron energy-loss spectroscopy combined with high-resolution transmission electron microscopy. Well-separated sharp peaks at the carbon K(1s) absorption edge and in the valence-loss spectra are obtained from a single freestanding carbon nanotube with the local chiral index and unambiguously identified as the transitions between the van Hove singularities. The spectra features clearly vary upon the different areas even in the individual carbon nanotube. Variations in interband transitions, plasmonic behaviors, and unoccupied electronic structures are clearly attributed to the local irregular atomic arrangement such as topological defect and/or elastic bond stretching.
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Affiliation(s)
- Ryosuke Senga
- Nano-Materials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565, Japan
| | - Thomas Pichler
- Faculty of Physics, University of Vienna , Strudlhofgasse 4, A-1090 Vienna, Austria
| | - Kazu Suenaga
- Nano-Materials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565, Japan
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26
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Bové H, Steuwe C, Fron E, Slenders E, D'Haen J, Fujita Y, Uji-I H, vandeVen M, Roeffaers M, Ameloot M. Biocompatible Label-Free Detection of Carbon Black Particles by Femtosecond Pulsed Laser Microscopy. NANO LETTERS 2016; 16:3173-8. [PMID: 27104759 DOI: 10.1021/acs.nanolett.6b00502] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Although adverse health effects of carbon black (CB) exposure are generally accepted, a direct, label-free approach for detecting CB particles in fluids and at the cellular level is still lacking. Here, we report nonincandescence related white-light (WL) generation by dry and suspended carbon black particles under illumination with femtosecond (fs) pulsed near-infrared light as a powerful tool for the detection of these carbonaceous materials. This observation is done for four different CB species with diameters ranging from 13 to 500 nm, suggesting this WL emission under fs near-infrared illumination is a general property of CB particles. As the emitted radiation spreads over the whole visible spectrum, detection is straightforward and flexible. The unique property of the described WL emission allows optical detection and unequivocal localization of CB particles in fluids and in cellular environments while simultaneously colocalizing different cellular components using various specific fluorophores as shown here using human lung fibroblasts. The experiments are performed on a typical multiphoton laser-scanning microscopy platform, widely available in research laboratories.
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Affiliation(s)
- Hannelore Bové
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590 Diepenbeek, Belgium
| | | | | | - Eli Slenders
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590 Diepenbeek, Belgium
| | - Jan D'Haen
- Institute for Material Research, Hasselt University , Wetenschapspark 1, 3950 Diepenbeek, Belgium
| | | | - Hiroshi Uji-I
- Research Institute for Electronic Science, Hokkaido University , N20W10, Kita-Ward Sapporo 001-0020, Japan
| | - Martin vandeVen
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590 Diepenbeek, Belgium
| | | | - Marcel Ameloot
- Biomedical Research Institute, Hasselt University , Agoralaan Building C, 3590 Diepenbeek, Belgium
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27
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Plasmon Excitations of Multi-layer Graphene on a Conducting Substrate. Sci Rep 2016; 6:21063. [PMID: 26883086 PMCID: PMC4756674 DOI: 10.1038/srep21063] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 01/13/2016] [Indexed: 11/23/2022] Open
Abstract
We predict the existence of low-frequency nonlocal plasmons at the vacuum-surface interface of a superlattice of N graphene layers interacting with conducting substrate. We derive a dispersion function that incorporates the polarization function of both the graphene monolayers and the semi-infinite electron liquid at whose surface the electrons scatter specularly. We find a surface plasmon-polariton that is not damped by particle-hole excitations or the bulk modes and which separates below the continuum mini-band of bulk plasmon modes. The surface plasmon frequency of the hybrid structure always lies below , the surface plasmon frequency of the conducting substrate. The intensity of this mode depends on the distance of the graphene layers from the conductor’s surface, the energy band gap between valence and conduction bands of graphene monolayer and, most importantly, on the number of two-dimensional layers. For a sufficiently large number of layers the hybrid structure has no surface plasmon. The existence of plasmons with different dispersion relations indicates that quasiparticles with different group velocity may coexist for various ranges of wavelengths determined by the number of layers in the superlattice.
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Cudazzo P, Sponza L, Giorgetti C, Reining L, Sottile F, Gatti M. Exciton Band Structure in Two-Dimensional Materials. PHYSICAL REVIEW LETTERS 2016; 116:066803. [PMID: 26919006 DOI: 10.1103/physrevlett.116.066803] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Indexed: 06/05/2023]
Abstract
Low-dimensional materials differ from their bulk counterparts in many respects. In particular, the screening of the Coulomb interaction is strongly reduced, which can have important consequences such as the significant increase of exciton binding energies. In bulk materials the binding energy is used as an indicator in optical spectra to distinguish different kinds of excitons, but this is not possible in low-dimensional materials, where the binding energy is large and comparable in size for excitons of very different localization. Here we demonstrate that the exciton band structure, which can be accessed experimentally, instead provides a powerful way to identify the exciton character. By comparing the ab initio solution of the many-body Bethe-Salpeter equation for graphane and single-layer hexagonal boron nitride, we draw a general picture of the exciton dispersion in two-dimensional materials, highlighting the different role played by the exchange electron-hole interaction and by the electronic band structure. Our interpretation is substantiated by a prediction for phosphorene.
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Affiliation(s)
- Pierluigi Cudazzo
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
| | - Lorenzo Sponza
- Department of Physics, King's College London, London WC2R 2LS, United Kingdom
| | - Christine Giorgetti
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
| | - Lucia Reining
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
| | - Francesco Sottile
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
| | - Matteo Gatti
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette, France
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Zhou JS, Kas JJ, Sponza L, Reshetnyak I, Guzzo M, Giorgetti C, Gatti M, Sottile F, Rehr JJ, Reining L. Dynamical effects in electron spectroscopy. J Chem Phys 2015; 143:184109. [DOI: 10.1063/1.4934965] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jianqiang Sky Zhou
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
| | - J. J. Kas
- European Theoretical Spectroscopy Facility (ETSF)
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Lorenzo Sponza
- Department of Physics, King’s College London, London WC2R 2LS, United Kingdom
| | - Igor Reshetnyak
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
| | - Matteo Guzzo
- Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin, D-12489 Berlin, Germany
| | - Christine Giorgetti
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
| | - Matteo Gatti
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette, France
| | - Francesco Sottile
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
| | - J. J. Rehr
- European Theoretical Spectroscopy Facility (ETSF)
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Lucia Reining
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM-IRAMIS, Université Paris-Saclay, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility (ETSF)
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30
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Wu JY, Lin CY, Gumbs G, Lin MF. The effect of perpendicular electric field on temperature-induced plasmon excitations for intrinsic silicene. RSC Adv 2015. [DOI: 10.1039/c5ra07721d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We use the tight-binding model and the random-phase approximation to investigate the intrinsic plasmon in silicene.
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Affiliation(s)
- Jhao-Ying Wu
- Department of Physics
- National Cheng Kung University
- Tainan
- Taiwan 701
| | - Chiun-Yan Lin
- Department of Physics
- National Cheng Kung University
- Tainan
- Taiwan 701
| | - Godfrey Gumbs
- Department of Physics and Astronomy
- Hunter College at the City University of New York
- New York 10065
- USA
| | - Ming-Fa Lin
- Department of Physics
- National Cheng Kung University
- Tainan
- Taiwan 701
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31
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Phan AD, Nga DT, Phan TL, Thanh LTM, Anh CT, Bernad S, Viet NA. Theoretical model for optical properties of porphyrin. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:062707. [PMID: 25615129 DOI: 10.1103/physreve.90.062707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Indexed: 06/04/2023]
Abstract
We propose a simple model to interpret the optical absorption spectra of porphyrin in different solvents. Our model successfully explains the decrease in the intensity of optical absorption at maxima of increased wavelengths. We also prove the dependence of the intensity and peak positions in the absorption spectra on the environment. The nature of the Soret band is supposed to derive from π plasmon. Our theoretical calculations are consistent with previous experimental studies.
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Affiliation(s)
- Anh D Phan
- Department of Physics, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801, USA and Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi 10000, Vietnam
| | - Do T Nga
- Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi 10000, Vietnam
| | - The-Long Phan
- Department of Physics, Chungbuk National University, Cheongju 361-763, Korea
| | - Le T M Thanh
- Faculty of Basic Science, Posts and Telecommunications Institute of Technology, 122 Hoang Quoc Viet, Hanoi 10000, Vietnam
| | - Chu T Anh
- Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi 10000, Vietnam
| | - Sophie Bernad
- Laboratoire de Chimie Physique, CNRS UMR 8000, Université Paris-Sud, 91405 Orsay Cedex, France
| | - N A Viet
- Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi 10000, Vietnam
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32
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Morimoto T, Joung SK, Saito T, Futaba DN, Hata K, Okazaki T. Length-dependent plasmon resonance in single-walled carbon nanotubes. ACS NANO 2014; 8:9897-9904. [PMID: 25283493 DOI: 10.1021/nn505430s] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The optical response of single-walled carbon nanotubes (SWCNTs) to far-infrared (FIR) radiation was systematically studied using various SWCNTs with different tube-length distributions. The observed peak position in the FIR spectra linearly scaled with the inverse of tube length irrespective of diameter, which is consistent with the dispersion relation predicted by the one-dimensional plasmon resonance model. The effects of chemical doping on the FIR spectra of the separated metallic and semiconducting SWCNTs clearly indicate that the motion of plasmons in the electronic band structures is primarily responsible for the optical response in these spectral regions. The observed absorption peaks are naturally sensitive to the presence of defects on the tube wall and correlated with the electric resistance, suggesting that the plasmons resonate with the current path length of the SWCNTs.
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Affiliation(s)
- Takahiro Morimoto
- Technology Research Association for Single Wall Carbon Nanotubes (TASC), Tsukuba 305-8565, Japan
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Abstract
Plasmons in graphene have unusual properties and offer promising prospects for plasmonic applications covering a wide frequency range, ranging from terahertz up to the visible. Plasmon modes have been recently studied in both free-standing and supported graphene. Here, we review plasmons in graphene with particular emphasis on plasmonic excitations in epitaxial graphene and on the influence of the underlying substrate on the screening processes. Although the theoretical comprehension of plasmons in supported graphene is still incomplete, several experimental results provide clues regarding the nature of plasmonic excitations in graphene on metals and semiconductors. Plasmon in graphene can be tuned by chemical doping and gating potentials. We show through selected examples that the adsorbates can be used to tune the plasmon frequency, while the intercalation of chemical species allows the decoupling of the graphene sheet from the substrate to recover the plasmon dispersion of pristine graphene. Finally, we also report intriguing effects due to many-body interaction, such as the excitations generated by electron-electron coupling (magnetoplasmons) and the composite modes arising from the coupling of plasmons with phonons and with charge carriers.
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Affiliation(s)
- Antonio Politano
- Università degli Studi della Calabria, Dipartimento di Fisica, 87036 Rende, CS, Italy.
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34
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Li C, Wang B, Yao Y, Piao G, Gu L, Wang Y, Duan X, Yu R. The structural transitions of C60 nanowhiskers under an electric field characterized by in situ transmission electron microscopy and electron energy-loss spectroscopy. NANOSCALE 2014; 6:6585-6589. [PMID: 24807127 DOI: 10.1039/c4nr00758a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In situ electrical transport measurements for individual C60 nanowhiskers are performed using a transmission electron microscope which monitors the crystal and electronic structural changes of the C60 nanowhiskers simultaneously. Electron diffraction combined with electron energy-loss spectroscopy shows that under the external electric current, the C60 nanowhiskers first transform from a face-centered-cubic structure to a disordered arrangement of C60 molecules. The cage structure of the C60 molecules then collapses to an amorphous carbon and finally, the amorphous carbon turns into graphene stacks. This process indicates the hybridization transformation from sp(2.278) to sp(2), which is different from the transition process of C60 materials under high pressure. The obtained results also suggest that the stability of the C60 nanowhiskers should be of crucial concern when they work as electrical devices.
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Affiliation(s)
- Chao Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603, Beijing 100190, P. R. China.
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Sato Y, Terauchi M. High-energy resolution electron energy-loss spectroscopy study of interband transitions characteristic to single-walled carbon nanotubes. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:807-814. [PMID: 24685359 DOI: 10.1017/s1431927614000580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
An electron energy-loss spectroscopic (EELS) study using a monochromator transmission electron microscope was conducted for investigating the dielectric response of isolated single-walled carbon nanotubes (SWCNTs) owing to interband transitions characteristic to chiral structures. Individual chiral structures of the SWCNTs were determined by electron diffraction patterns. EELS spectra obtained from isolated SWCNTs showed sharp peaks below π plasmon energy of 5 eV, which were attributed to the characteristic interband transitions of SWCNTs. In addition, unexpected shoulder structures were observed at the higher energy side of each sharp peak. Simulations of EELS spectra by using the continuum dielectric theory showed that an origin of the shoulder structures was because of the surface dipole mode along the circumference direction of the SWCNT. It was noticed that the electron excitation energies obtained by EELS were slightly higher than those of optical studies, which might be because of the inelastic scattering process with the momentum transfers. To interpret the discrepancy between the EELS and optical experiments, it is necessary to conduct more accurate simulation including the first principle calculation for the band structure of SWCNTs.
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Affiliation(s)
- Yohei Sato
- Institute of Multidisciplinary Research for Advanced Materials,Tohoku University,1,1 Katahira,2-Chome,Aobaku,Sendai 980-8577,Japan
| | - Masami Terauchi
- Institute of Multidisciplinary Research for Advanced Materials,Tohoku University,1,1 Katahira,2-Chome,Aobaku,Sendai 980-8577,Japan
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36
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Stauber T. Plasmonics in Dirac systems: from graphene to topological insulators. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:123201. [PMID: 24598974 DOI: 10.1088/0953-8984/26/12/123201] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Recent developments in the emerging field of plasmonics in graphene and other Dirac systems are reviewed and a comprehensive introduction to the standard models and techniques is given. In particular, we discuss intrinsic plasmon excitation of single and bilayer graphene via hydrodynamic equations and the random phase approximation, but also comment on double and multilayer structures. Additionally, we address Dirac systems in the retardation limit and also with large spin–orbit coupling including topological insulators. Finally, we summarize basic properties of the charge, current and photon linear response functions in an appendix.
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37
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Kramberger C, Thurakitseree T, Maruyama S, Knupfer M. π and π + σ plasmon localization in single-walled carbon nanotube meta-materials. NANOTECHNOLOGY 2013; 24:405202. [PMID: 24029462 DOI: 10.1088/0957-4484/24/40/405202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We have investigated the plasmon excitations and interband transitions in nematic nanotube meta-materials with different nanotube mean diameters. While the characteristic optical low-energy transitions give testimony to the differing mean diameters, the full momentum resolved π as well as π + σ plasmon response of the meta-materials is found to be entirely invariant with the nanotube diameters 1 nm < d < 2 nm. We hence demonstrate that plasmons on single-walled carbon nanotubes are fully channeled to be one dimensional in the typical range of nanotube diameters. The internal morphology of the meta-material offers a knob to uniformly tune the plasmon resonances.
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Affiliation(s)
- C Kramberger
- Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090, Vienna, Austria. IFW Dresden, Helmholtzstraße 20, D-01069 Dresden, Germany
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38
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Segui S, Mišković ZL, Gervasoni JL, Arista NR. Plasmon excitation in single-walled carbon nanotubes probed using charged particles: comparison of calculated and experimental spectra. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:175001. [PMID: 23503302 DOI: 10.1088/0953-8984/25/17/175001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We study ' the excitation of plasmons due to the incidence of a fast charged particle that passes through a single-wall carbon nanotube. We use a quantized hydrodynamic model, in which the σ and π electron systems are depicted as two interacting fluids moving on a cylindrical surface. Calculations of the average number of the excited plasmons and the corresponding energy loss probability for the swift electrons are compared with several experimental results for electron energy loss spectra recorded using transmission electron microscopes. We are able to identify the π and σ + π plasmon peaks and elucidate the origin of various spectral features observed in different experiments.
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Affiliation(s)
- Silvina Segui
- Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Argentina.
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39
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Spataru CD, Léonard F. Quasiparticle and exciton renormalization effects in electrostatically doped semiconducting carbon nanotubes. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.08.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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40
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Politano A, Campi D, Formoso V, Chiarello G. Evidence of confinement of the π plasmon in periodically rippled graphene on Ru(0001). Phys Chem Chem Phys 2013; 15:11356-61. [PMID: 23736309 DOI: 10.1039/c3cp51954f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Antonio Politano
- Dipartimento di Fisica, Università degli Studi della Calabria, 87036 Rende, Cs, Italy
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41
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Camilli L, Scarselli M, Gobbo SD, Castrucci P, Gautron E, De Crescenzi M. Structural, electronic and photovoltaic characterization of multiwalled carbon nanotubes grown directly on stainless steel. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2012; 3:360-367. [PMID: 23016140 PMCID: PMC3388360 DOI: 10.3762/bjnano.3.42] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 03/29/2012] [Indexed: 06/01/2023]
Abstract
We have taken advantage of the native surface roughness and the iron content of AISI-316 stainless steel to grow multiwalled carbon nanotubes (MWCNTs) by chemical vapour deposition without the addition of an external catalyst. The structural and electronic properties of the synthesized carbon nanostructures have been investigated by a range of electron microscopy and spectroscopy techniques. The results show the good quality and the high graphitization degree of the synthesized MWCNTs. Through energy-loss spectroscopy we found that the electronic properties of these nanostructures are markedly different from those of highly oriented pyrolytic graphite (HOPG). Notably, a broadening of the π-plasmon peak in the case of MWCNTs is evident. In addition, a photocurrent was measured when MWCNTs were airbrushed onto a silicon substrate. External quantum efficiency (EQE) and photocurrent values were reported both in planar and in top-down geometry of the device. Marked differences in the line shapes and intensities were found for the two configurations, suggesting that two different mechanisms of photocurrent generation and charge collection are in operation. From this comparison, we are able to conclude that the silicon substrate plays an important role in the production of electron-hole pairs.
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Affiliation(s)
- Luca Camilli
- Dipartimento di Fisica, Università di Roma Tor Vergata, 00133 Roma, Italy
| | - Manuela Scarselli
- Dipartimento di Fisica, Università di Roma Tor Vergata, 00133 Roma, Italy
| | - Silvano Del Gobbo
- Dipartimento di Fisica, Università di Roma Tor Vergata, 00133 Roma, Italy
| | - Paola Castrucci
- Dipartimento di Fisica, Università di Roma Tor Vergata, 00133 Roma, Italy
| | - Eric Gautron
- Institut des Matériaux Jean Rouxel, CNRS-UMR 6502, 44322 Nantes Cedex 3, France
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42
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Cocchi C, Prezzi D, Ruini A, Benassi E, Caldas MJ, Corni S, Molinari E. Optical Excitations and Field Enhancement in Short Graphene Nanoribbons. J Phys Chem Lett 2012; 3:924-929. [PMID: 26286422 DOI: 10.1021/jz300164p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The optical excitations of elongated graphene nanoflakes of finite length are investigated theoretically through quantum chemistry semiempirical approaches. The spectra and the resulting dipole fields are analyzed, accounting in full atomistic details for quantum confinement effects, which are crucial in the nanoscale regime. We find that the optical spectra of these nanostructures are dominated at low energy by excitations with strong intensity, comprised of characteristic coherent combinations of a few single-particle transitions with comparable weight. They give rise to stationary collective oscillations of the photoexcited carrier density extending throughout the flake and to a strong dipole and field enhancement. This behavior is robust with respect to width and length variations, thus ensuring tunability in a large frequency range. The implications for nanoantennas and other nanoplasmonic applications are discussed for realistic geometries.
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Affiliation(s)
- Caterina Cocchi
- †Centro S3, CNR-Istituto Nanoscienze, I-41125 Modena, Italy
- ‡Dipartimento di Fisica, Università di Modena e Reggio Emilia, I-41125 Modena, Italy
| | - Deborah Prezzi
- †Centro S3, CNR-Istituto Nanoscienze, I-41125 Modena, Italy
| | - Alice Ruini
- †Centro S3, CNR-Istituto Nanoscienze, I-41125 Modena, Italy
- ‡Dipartimento di Fisica, Università di Modena e Reggio Emilia, I-41125 Modena, Italy
| | - Enrico Benassi
- †Centro S3, CNR-Istituto Nanoscienze, I-41125 Modena, Italy
| | - Marilia J Caldas
- ¶Instituto de Física, Universidade de São Paulo, 05508-900 São Paulo, SP, Brazil
| | - Stefano Corni
- †Centro S3, CNR-Istituto Nanoscienze, I-41125 Modena, Italy
| | - Elisa Molinari
- †Centro S3, CNR-Istituto Nanoscienze, I-41125 Modena, Italy
- ‡Dipartimento di Fisica, Università di Modena e Reggio Emilia, I-41125 Modena, Italy
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43
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Mahns B, Roth F, Grobosch M, Zahn DRT, Knupfer M. Electronic excitations of potassium intercalated manganese phthalocyanine investigated by electron energy-loss spectroscopy. J Chem Phys 2011; 134:194504. [PMID: 21599070 DOI: 10.1063/1.3591347] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Yan J, Thygesen KS, Jacobsen KW. Nonlocal screening of plasmons in graphene by semiconducting and metallic substrates: first-principles calculations. PHYSICAL REVIEW LETTERS 2011; 106:146803. [PMID: 21561211 DOI: 10.1103/physrevlett.106.146803] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Indexed: 05/22/2023]
Abstract
We investigate the role of substrates on the collective excitations of graphene by using a first-principles implementation of the density response function within the random-phase approximation. Specifically, we consider graphene adsorbed on SiC(0001) and Al(111) as representative examples of a semiconducting and metallic substrate. On SiC(0001), the long wavelength π plasmons are significantly damped although their energies remain almost unaltered. On Al(111), the long wavelength π plasmons are completely quenched due to the coupling to the metal surface plasmon. The strong damping of the plasmon excitations occurs despite the fact that the single-particle band structure of graphene is completely unaffected by the substrates illustrating the nonlocal nature of the effect.
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Affiliation(s)
- Jun Yan
- Center for Atomic-scale Materials Design, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
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45
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Castrucci P, Scilletta C, Del Gobbo S, Scarselli M, Camilli L, Simeoni M, Delley B, Continenza A, De Crescenzi M. Light harvesting with multiwall carbon nanotube/silicon heterojunctions. NANOTECHNOLOGY 2011; 22:115701. [PMID: 21297234 DOI: 10.1088/0957-4484/22/11/115701] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We report on a significant photocurrent generation from a planar device obtained by coating a bare n doped silicon substrate with a random network of multiwall carbon nanotubes (MWCNTs). This MWCNT/n-Si hybrid device exhibits an incident photon to current efficiency reaching up to 34% at 670 nm. We also show that MWCNTs covering a quartz substrate still exhibit photocurrent, though well below than that of the MWCNTs coating the silicon substrate. These results suggest that MWCNTs are able to generate photocurrent and that the silicon substrate plays a fundamental role in our planar device. The former effect is particularly interesting because MWCNTs are generally known to mimic the electronic properties of graphite, which does not present any photocurrent generation. On the basis of theoretical calculations revealing a weak metallic character for MWCNTs, we suggest that both metallic and semiconducting nanotubes are able to generate e-h pairs upon illumination. This can be ascribed to the presence of van Hove singularities in the density of states of each single wall carbon nanotube constituting the MWCNT and to the low density of electrons at the Fermi level. Finally, we suggest that though both MWCNTs and Si substrate are involved in the photocurrent generation process, MWCNT film mainly acts as a semitransparent electrode in our silicon-based device.
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Affiliation(s)
- Paola Castrucci
- Dipartimento di Fisica and Unità CNISM, Università di Roma Tor Vergata, Roma, Italy.
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Sun J, Hannon JB, Tromp RM, Johari P, Bol AA, Shenoy VB, Pohl K. Spatially-resolved structure and electronic properties of graphene on polycrystalline Ni. ACS NANO 2010; 4:7073-7077. [PMID: 21062038 DOI: 10.1021/nn102167f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have used in situ low-energy electron microscopy (LEEM) to correlate the atomic and electronic structure of graphene films on polycrystalline Ni with nm-scale spatial resolution. Spatially resolved electron scattering measurements show that graphene monolayers formed by carbon segregation do not support the π-plasmon of graphene, indicating strong covalent bonding to the Ni. Graphene bilayers have the Bernal stacking characteristic of graphite and show the expected plasmon loss at 6.5 eV. The experimental results, in agreement with first-principles calculations, show that the π-band structure of free-standing graphene appears only in films with a thickness of at least two layers and demonstrate the sensitivity of the plasmon loss to the electronic structure.
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Affiliation(s)
- Jiebing Sun
- Physics Department and Materials Science Program, University of New Hampshire, Durham, New Hampshire 03824, USA
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Horing NJM. Aspects of the theory of graphene. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:5525-5556. [PMID: 21041228 DOI: 10.1098/rsta.2010.0242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Following a brief review of the device-friendly features of graphene, recent work on its Green's functions with and without a normal magnetic field are discussed, for an infinite graphene sheet and also for a quantum dot, with analyses of the Landau-quantized energy spectra of the sheet and dot. The random phase approximation dielectric response of graphene is reviewed and discussed in connection with the van der Waals interactions of a graphene sheet with atoms/molecules and with a second graphene sheet in a double layer. Energy-loss spectroscopy for a graphene sheet subject to both parallel and perpendicular particle probes of its dynamic, non-local response properties are also treated. Furthermore, we discuss recent work on the coupling of a graphene plasmon and a surface plasmon, yielding a collective plasma mode that is linear in wavenumber. Finally, we discuss the unusual aspects of graphene conduction and recent work on diffusive charge transport in graphene, in both the DC and AC regimes.
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Hwang SW, Shin DH, Kim CO, Hong SH, Kim MC, Kim J, Lim KY, Kim S, Choi SH, Ahn KJ, Kim G, Sim SH, Hong BH. Plasmon-enhanced ultraviolet photoluminescence from hybrid structures of graphene/ZnO films. PHYSICAL REVIEW LETTERS 2010; 105:127403. [PMID: 20867671 DOI: 10.1103/physrevlett.105.127403] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Indexed: 05/09/2023]
Abstract
We report substantially enhanced photoluminescence (PL) from hybrid structures of graphene/ZnO films at a band gap energy of ZnO (∼3.3 eV/376 nm). Despite the well-known constant optical conductivity of graphene in the visible-frequency regime, its abnormally strong absorption in the violet-frequency region has recently been reported. In this Letter, we demonstrate that the resonant excitation of graphene plasmon is responsible for such absorption and eventually contributes to enhanced photoemission from structures of graphene/ZnO films when the corrugation of the ZnO surface modulates photons emitted from ZnO to fulfill the dispersion relation of graphene plasmon. These arguments are strongly supported by PL enhancements depending on the spacer thickness, measurement temperature, and annealing temperature, and the micro-PL mapping images obtained from separate graphene layers on ZnO films.
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Affiliation(s)
- Sung Won Hwang
- Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701, Korea
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Castrucci P, Scarselli M, De Crescenzi M, El Khakani MA, Rosei F. Probing the electronic structure of carbon nanotubes by nanoscale spectroscopy. NANOSCALE 2010; 2:1611-1625. [PMID: 20820691 DOI: 10.1039/c0nr00111b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Among the carbon allotropes newly discovered during the last few decades, carbon nanotubes (CNTs) have attracted enormous attention due to their structural and electronic properties with strong one dimensional character. The physical and chemical features of such systems are intrinsically rich and complex, and can only be probed by using multiple experimental and theoretical techniques. In this feature, we focus on the structural and electronic properties of CNTs that can be accessed by using transmission electron energy loss spectroscopies. The latter are complementary to optical and X-ray absorption techniques, yet allow to obtain the electronic structure with nanoscale spatial resolution. An improved understanding of the structure-electronic properties relationship of these unique 1D systems would represent a fundamental advance, and holds the promise of using CNTs in future applications.
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Affiliation(s)
- Paola Castrucci
- Dipartimento di Fisica, Unità CNISM, Università di Roma Tor Vergata, Roma, Italy.
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Rance GA, Marsh DH, Nicholas RJ, Khlobystov AN. UV–vis absorption spectroscopy of carbon nanotubes: Relationship between the π-electron plasmon and nanotube diameter. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.05.012] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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