1
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Jorudas J, Rehman H, Cojocari M, Pashnev D, Urbanowicz A, Kašalynas I, Bertoni B, Vicarelli L, Pitanti A, Malykhin S, Svirko Y, Kuzhir P, Fedorov G. Ultra-broadband absorbance of nanometer-thin pyrolyzed-carbon film on silicon nitride membrane. NANOTECHNOLOGY 2024; 35:305705. [PMID: 38648779 DOI: 10.1088/1361-6528/ad4157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 04/22/2024] [Indexed: 04/25/2024]
Abstract
Fifty percents absorption by thin film, with thickness is much smaller than the skin depth and optical thickness much smaller than the wavelength, is a well-known concept of classical electrodynamics. This is a valuable feature that has been numerously widely explored for metal films, while chemically inert nanomembranes are a real fabrication challenge. Here we report the 20 nm thin pyrolyzed carbon film (PyC) placed on 300 nm thick silicon nitride (Si3N4) membrane demonstrating an efficient broadband absorption in the terahertz and near infrared ranges. While the bare Si3N4membrane is completely transparent in the THz range, the 20 nm thick PyC layer increases the absorption of the PyC coated Si3N4membrane to 40%. The reflection and transmission spectra in the near infrared region reveal that the PyC film absorption persists to a level of at least 10% of the incident power. Such a broadband absorption of the PyC film opens new pathways toward broadband bolometric radiation detectors.
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Affiliation(s)
- Justinas Jorudas
- Department of Physics and Mathematics, Center of Photonics Research, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
- Department of Optoelectronics, Center for Physical Sciences and Technology (FTMC), Saulėtekio av. 3, LT-10257 Vilnius, Lithuania
| | - Hamza Rehman
- Department of Physics and Mathematics, Center of Photonics Research, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
| | - Maria Cojocari
- Department of Physics and Mathematics, Center of Photonics Research, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
| | - Daniil Pashnev
- Department of Optoelectronics, Center for Physical Sciences and Technology (FTMC), Saulėtekio av. 3, LT-10257 Vilnius, Lithuania
| | - Andrzej Urbanowicz
- Department of Optoelectronics, Center for Physical Sciences and Technology (FTMC), Saulėtekio av. 3, LT-10257 Vilnius, Lithuania
- UAB 'TERAVIL', Savanoriu av. 235, LT-02300, Vilnius, Lithuania
| | - Irmantas Kašalynas
- Department of Optoelectronics, Center for Physical Sciences and Technology (FTMC), Saulėtekio av. 3, LT-10257 Vilnius, Lithuania
- Institute of Applied Electrodynamics and Telecommunications, Vilnius University, Saulėtekio al. 3, 10257 Vilnius, Lithuania
| | - Benedetta Bertoni
- Dipartimento di Fisica, Università di Pisa, largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
| | - Leonardo Vicarelli
- Dipartimento di Fisica, Università di Pisa, largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
| | - Alessandro Pitanti
- Dipartimento di Fisica, Università di Pisa, largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
- NEST, CNR-Istituto Nanoscienze, piazza San Silvestro 12, I-56127 Pisa, Italy
| | - Sergei Malykhin
- Department of Physics and Mathematics, Center of Photonics Research, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
| | - Yuri Svirko
- Department of Physics and Mathematics, Center of Photonics Research, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
| | - Polina Kuzhir
- Department of Physics and Mathematics, Center of Photonics Research, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
| | - Georgy Fedorov
- Department of Physics and Mathematics, Center of Photonics Research, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
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2
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Pasanen H, Khan R, Odutola JA, Tkachenko NV. Transient Absorption Spectroscopy of Films: Impact of Refractive Index. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:6167-6179. [PMID: 38655057 PMCID: PMC11037419 DOI: 10.1021/acs.jpcc.4c00981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/19/2024] [Accepted: 03/21/2024] [Indexed: 04/26/2024]
Abstract
Transient absorption spectroscopy is a powerful technique to study the photoinduced phenomena in a wide range of states from solutions to solid film samples. It was designed and developed based on photoinduced absorption changes or that photoexcitation triggers a chain of reactions with intermediate states or reaction steps with presumably different absorption spectra. However, according to general electromagnetic theory, any change in the absorption properties of a medium is accompanied by a change in the refractive properties. Although this photoinduced change in refractive index has a negligible effect on solution measurements, it may significantly affect the measured response of thin films. In this Perspective paper, we examine why and how the measured responses of films differ from their expected "pure" absorption responses. The effect of photoinduced refractive index change can be concluded and studied by comparing the transmitted and reflected probe light responses. Another discussed aspect is the effect of light interference on thin films. Finally, new opportunities of monitoring the photocarrier migration in films and studying nontransparent samples using the reflected probe light response are discussed. Most of the examples provided in this article focus on studies involving perovskite, TiO2, and graphene-based films, but the general discussion and conclusions can be applicable to a wide range of semiconductor and thin metallic films.
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Affiliation(s)
- Hannu
P. Pasanen
- Ultrafast
Dynamics Group Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 4700, Kingdom of Saudi Arabia
| | - Ramsha Khan
- Chemistry
and Advanced Materials Group Faculty of Engineering and Natural Sciences, Tampere University, Tampere 33014, Finland
| | - Jokotadeola A. Odutola
- Chemistry
and Advanced Materials Group Faculty of Engineering and Natural Sciences, Tampere University, Tampere 33014, Finland
| | - Nikolai V. Tkachenko
- Chemistry
and Advanced Materials Group Faculty of Engineering and Natural Sciences, Tampere University, Tampere 33014, Finland
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3
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Odutola J, Szalad H, Albero J, García H, Tkachenko NV. Long-Lived Photo-Response of Multi-Layer N-Doped Graphene-Based Films. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:17896-17905. [PMID: 37736291 PMCID: PMC10510389 DOI: 10.1021/acs.jpcc.3c04670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 08/17/2023] [Indexed: 09/23/2023]
Abstract
New insights into the mechanism of the improved photo(electro)catalytic activity of graphene by heteroatom doping were explored by transient transmittance and reflectance spectroscopy of multi-layer N-doped graphene-based samples on a quartz substrate prepared by chitosan pyrolysis in the temperature range 900-1200 °C compared to an undoped graphene control. All samples had an expected photo-response: fast relaxation (within 1 ps) due to decreased plasmon damping and increased conductivity. However, the N-doped graphenes had an additional transient absorption signal of roughly 10 times lower intensity, with 10-50 ps formation time and the lifetime extending into the nanosecond domain. These photo-induced responses were recalculated as (complex) dielectric function changes and decomposed into Drude-Lorentz parameters to derive the origin of the opto(electronic) responses. Consequently, the long-lived responses were revealed to have different dielectric function spectra from those of the short-lived responses, which was ultimately attributed to electron trapping at doping centers. These trapped electrons are presumed to be responsible for the improved catalytic activity of multi-layer N-doped graphene-based films compared to that of multi-layer undoped graphene-based films.
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Affiliation(s)
- Jokotadeola
A. Odutola
- Photonics
Compound and Nanomaterials (Chemistry and Advanced Materials Group),
Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, FI-33720 Tampere, Finland
| | - Horatiu Szalad
- Instituto
Universitario de Tecnología Química, Universitat Politècnica de València, Avda. de los Naranjos s/n, 46022 Valencia, Spain
| | - Josep Albero
- Instituto
Universitario de Tecnología Química, Universitat Politècnica de València, Avda. de los Naranjos s/n, 46022 Valencia, Spain
| | - Hermenegildo García
- Instituto
Universitario de Tecnología Química, Universitat Politècnica de València, Avda. de los Naranjos s/n, 46022 Valencia, Spain
| | - Nikolai V. Tkachenko
- Photonics
Compound and Nanomaterials (Chemistry and Advanced Materials Group),
Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, FI-33720 Tampere, Finland
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4
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Liu HY, Wu JY. Tunable Electronic Properties of Two-Dimensional GaSe 1-xTe x Alloys. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:818. [PMID: 36903697 PMCID: PMC10005243 DOI: 10.3390/nano13050818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 02/18/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
In this work, we performed a theoretical study on the electronic properties of monolayer GaSe1-xTex alloys using the first-principles calculations. The substitution of Se by Te results in the modification of a geometric structure, charge redistribution, and bandgap variation. These remarkable effects originate from the complex orbital hybridizations. We demonstrate that the energy bands, the spatial charge density, and the projected density of states (PDOS) of this alloy are strongly dependent on the substituted Te concentration.
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Affiliation(s)
- Hsin-Yi Liu
- Department of Physics/QTC/Hi-GEM, National Cheng Kung University, Tainan 701, Taiwan
| | - Jhao-Ying Wu
- Center of General Studies, National Kaohsiung University of Science and Technology, Kaohsiung 811, Taiwan
- Department of Energy and Refrigerating Air-Conditioning Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 811, Taiwan
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5
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Liu HY, Wu JY. Feature-Rich Electronic Properties of Sliding Bilayer Germanene. ACS OMEGA 2022; 7:42304-42312. [PMID: 36440158 PMCID: PMC9686190 DOI: 10.1021/acsomega.2c05219] [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: 08/14/2022] [Accepted: 10/31/2022] [Indexed: 06/16/2023]
Abstract
This study employs first-principles calculations to elucidate the properties of sliding bilayer germanene (BLGe). The buckled structure of germanene can afford a greater number of metastable stacking configurations than planar graphene and enrich the electronic properties. Herein, a detailed analysis of the structural variety, shift-dependent energy bands, and spatial charge densities of BLGe is presented. The projected density of states (PDOS) reveals diverse structures such as plateaus, dips, symmetric/asymmetric peaks, and shoulders. The low-lying ones of the prominent structures could correspond to single or multiorbital hybridization, depending on the stacking configuration.
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Affiliation(s)
- Hsin-Yi Liu
- Department
of Physics/QTC/Hi-GEM, National Cheng Kung
University, Tainan 70148, Taiwan
| | - Jhao-Ying Wu
- Center
of General Studies, National Kaohsiung University
of Science and Technology, Kaohsiung 811213, Taiwan
- Department
of Energy and Refrigerating Air-Conditioning Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 811213, Taiwan
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6
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Ganguli S, Sekretareva A. Role of an Inert Electrode Support in Plasmonic Electrocatalysis. ACS Catal 2022. [DOI: 10.1021/acscatal.2c00206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sagar Ganguli
- Department of Chemistry, Ångström Laboratory, Molecular Biomimetics, Uppsala University, 75120 Uppsala, Sweden
| | - Alina Sekretareva
- Department of Chemistry, Ångström Laboratory, Molecular Biomimetics, Uppsala University, 75120 Uppsala, Sweden
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7
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Michaud V, Pracht J, Schilfarth F, Damm C, Platzer B, Haines P, Harreiß C, Guldi DM, Spiecker E, Peukert W. Well-separated water-soluble carbon dots via gradient chromatography. NANOSCALE 2021; 13:13116-13128. [PMID: 34477795 DOI: 10.1039/d1nr02562g] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Carbon dots (CDs) are strongly fluorescent advanced materials that are promising for applications in bio-imaging, sensors or luminescent displays. One of the most-widely used class of CDs is synthesized via an aqueous, bottom-up technique starting from citric acid (CA) and an amino-precursor. Very high fluorescence quantum yields (QY) are reported for the resulting CDs. The as-synthesized raw suspensions, however, are crude mixtures of many components: bare carbon cores, carbon cores functionalized with fluorophores, freely floating molecular fluorophores, and several other by-products. In this study, we synthesized CDs from CA and amino acid cysteine (Cys) hydrothermally and demonstrate a complete separation of all components by means of two step gradient chromatography. In the first step, the separation was carried out on a normal-pressure preparative silica-gel column to get sufficient amounts of material to investigate structure and optical properties of the collected fractions. This preparative gradient elution method enabled us to separate moderately-fluorescent CDs from freely floating molecular fluorophores, polymeric fluorophores and CDs with built-in fluorophores. Here, we evidenced that amorphous CDs co-exist with crystalline CDs in one and the same suspension and showed that the amount of crystalline CDs increases with the synthesis temperature. In the second step, we turned to high performance liquid chromatography (HPLC) to further improve and optimize the efficiency of purification and automate it. Via HPLC, we were able to well-separate of up to six components. Within this work, we laid the foundation for CD purification with the highest possible purity for aqueous, bottom-up synthesized CDs and quantified the true quantum yield of CDs.
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Affiliation(s)
- Vanessa Michaud
- Friedrich-Alexander University Erlangen-Nürnberg, Institute of Particle Technology, Cauerstrasse 4, 91058 Erlangen, Germany.
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8
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Liu HY, Lin SY, Wu JY. Stacking-configuration-enriched essential properties of bilayer graphenes and silicenes. J Chem Phys 2020; 153:154707. [PMID: 33092355 DOI: 10.1063/5.0024421] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
First-principles calculations show that the geometric and electronic properties of silicene-related systems have diversified phenomena. Critical factors of group-IV monoelements, like buckled/planar structures, stacking configurations, layer numbers, and van der Waals interactions of bilayer composites, are considered simultaneously. The theoretical framework developed provides a concise physical and chemical picture. Delicate evaluations and analyses have been made on the optimal lattices, energy bands, and orbital-projected van Hove singularities. They provide decisive mechanisms, such as buckled/planar honeycomb lattices, multi-/single-orbital hybridizations, and significant/negligible spin-orbital couplings. We investigate the stacking-configuration-induced dramatic transformations of essential properties by relative shift in bilayer graphenes and silicenes. The lattice constant, interlayer distance, buckling height, and total energy essentially depend on the magnitude and direction of the relative shift: AA → AB → AA' → AA. Apparently, sliding bilayer systems are quite different between silicene and graphene in terms of geometric structures, electronic properties, orbital hybridizations, interlayer hopping integrals, and spin interactions.
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Affiliation(s)
- Hsin-Yi Liu
- Department of Physics/QTC/Hi-GEM, National Cheng Kung University, Tainan, Taiwan
| | - Shih-Yang Lin
- Department of Physics, National Chung Cheng University, Chiayi, Taiwan
| | - Jhao-Ying Wu
- Center of General Studies, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
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9
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Golubewa L, Rehman H, Kulahava T, Karpicz R, Baah M, Kaplas T, Shah A, Malykhin S, Obraztsov A, Rutkauskas D, Jankunec M, Matulaitienė I, Selskis A, Denisov A, Svirko Y, Kuzhir P. Macro-, Micro- and Nano-Roughness of Carbon-Based Interface with the Living Cells: Towards a Versatile Bio-Sensing Platform. SENSORS (BASEL, SWITZERLAND) 2020; 20:E5028. [PMID: 32899745 PMCID: PMC7570712 DOI: 10.3390/s20185028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/27/2020] [Accepted: 09/02/2020] [Indexed: 12/20/2022]
Abstract
Integration of living cells with nonbiological surfaces (substrates) of sensors, scaffolds, and implants implies severe restrictions on the interface quality and properties, which broadly cover all elements of the interaction between the living and artificial systems (materials, surface modifications, drug-eluting coatings, etc.). Substrate materials must support cellular viability, preserve sterility, and at the same time allow real-time analysis and control of cellular activity. We have compared new substrates based on graphene and pyrolytic carbon (PyC) for the cultivation of living cells. These are PyC films of nanometer thickness deposited on SiO2 and black silicon and graphene nanowall films composed of graphene flakes oriented perpendicular to the Si substrate. The structure, morphology, and interface properties of these substrates are analyzed in terms of their biocompatibility. The PyC demonstrates interface biocompatibility, promising for controlling cell proliferation and directional intercellular contact formation while as-grown graphene walls possess high hydrophobicity and poor biocompatibility. By performing experiments with C6 glioma cells we discovered that PyC is a cell-friendly coating that can be used without poly-l-lysine or other biopolymers for controlling cell adhesion. Thus, the opportunity to easily control the physical/chemical properties and nanotopography makes the PyC films a perfect candidate for the development of biosensors and 3D bioscaffolds.
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Affiliation(s)
- Lena Golubewa
- Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania; (L.G.); (R.K.); (D.R.); (I.M.); (A.S.)
- Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, 220030 Minsk, Belarus;
| | - Hamza Rehman
- Institute of Photonics, University of Eastern Finland, Yliopistokatu 2, FI-80100 Joensuu, Finland; (H.R.); (M.B.); (T.K.); (S.M.); (A.O.); (Y.S.)
| | - Tatsiana Kulahava
- Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, 220030 Minsk, Belarus;
- Department of Biophysics, Belarusian State University, Nezavisimosti Ave. 4, 220030 Minsk, Belarus;
| | - Renata Karpicz
- Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania; (L.G.); (R.K.); (D.R.); (I.M.); (A.S.)
| | - Marian Baah
- Institute of Photonics, University of Eastern Finland, Yliopistokatu 2, FI-80100 Joensuu, Finland; (H.R.); (M.B.); (T.K.); (S.M.); (A.O.); (Y.S.)
| | - Tommy Kaplas
- Institute of Photonics, University of Eastern Finland, Yliopistokatu 2, FI-80100 Joensuu, Finland; (H.R.); (M.B.); (T.K.); (S.M.); (A.O.); (Y.S.)
| | - Ali Shah
- Department of Micro and Nanosciences, Aalto University, FI-00076 Espoo, P.O. Box 13500, Finland;
| | - Sergei Malykhin
- Institute of Photonics, University of Eastern Finland, Yliopistokatu 2, FI-80100 Joensuu, Finland; (H.R.); (M.B.); (T.K.); (S.M.); (A.O.); (Y.S.)
- Division of Solid State Physics, Lebedev Physical Institute of the Russian Academy of Sciences, Leninskiy Prospekt 53, 119991 Moscow, Russia
- Department of Physics, Lomonosov Moscow State University, Leninskie gory 1–2, 119991 Moscow, Russia
| | - Alexander Obraztsov
- Institute of Photonics, University of Eastern Finland, Yliopistokatu 2, FI-80100 Joensuu, Finland; (H.R.); (M.B.); (T.K.); (S.M.); (A.O.); (Y.S.)
- Department of Physics, Lomonosov Moscow State University, Leninskie gory 1–2, 119991 Moscow, Russia
| | - Danielis Rutkauskas
- Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania; (L.G.); (R.K.); (D.R.); (I.M.); (A.S.)
| | - Marija Jankunec
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Sauletekio Ave. 7, LT-10257 Vilnius, Lithuania;
| | - Ieva Matulaitienė
- Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania; (L.G.); (R.K.); (D.R.); (I.M.); (A.S.)
| | - Algirdas Selskis
- Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania; (L.G.); (R.K.); (D.R.); (I.M.); (A.S.)
| | - Andrei Denisov
- Department of Biophysics, Belarusian State University, Nezavisimosti Ave. 4, 220030 Minsk, Belarus;
- Institute of Physiology of the National Academy of Sciences of Belarus, Minsk, Belarus, 28 Akademichnaya Str., BY-220072 Minsk, Belarus
| | - Yuri Svirko
- Institute of Photonics, University of Eastern Finland, Yliopistokatu 2, FI-80100 Joensuu, Finland; (H.R.); (M.B.); (T.K.); (S.M.); (A.O.); (Y.S.)
| | - Polina Kuzhir
- Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, 220030 Minsk, Belarus;
- Institute of Photonics, University of Eastern Finland, Yliopistokatu 2, FI-80100 Joensuu, Finland; (H.R.); (M.B.); (T.K.); (S.M.); (A.O.); (Y.S.)
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10
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Adjustable optical transmittance of superhydrophobic carbon soot coatings by in-situ single-step control of their physicochemical profile. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.01.048] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Nojeh A, Sawatzky GA, Whitehead LA. Graphene-based bidirectional radiative thermal transfer method for heat engines. APPLIED OPTICS 2019; 58:2028-2032. [PMID: 30874070 DOI: 10.1364/ao.58.002028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/01/2019] [Indexed: 06/09/2023]
Abstract
We present a method for substantially enhancing the rate of heat transfer into and out of the working fluid of a heat engine, using bidirectional thermal radiation exchange between the external environment and many individual graphene layers that are dispersed and suspended within an inert gas. This hybrid working fluid has the unique composite property of high optical absorption/emission yet low specific heat. Consequently, it can heat and cool rapidly, enabling a much greater cycle frequency and a commensurate increase in specific power, in comparison to conventional closed-cycle heat engines for which the cycle frequency is limited by the use of slower, non-radiative, thermal transfer.
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12
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Nguyen J, Conca DV, Stein J, Bovo L, Howard CA, Llorente Garcia I. Magnetic control of graphitic microparticles in aqueous solutions. Proc Natl Acad Sci U S A 2019; 116:2425-2434. [PMID: 30683726 PMCID: PMC6377480 DOI: 10.1073/pnas.1817989116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Graphite is an inexpensive material with useful electrical, magnetic, thermal, and optical properties. It is also biocompatible and used universally as a substrate. Micrometer-sized graphitic particles in solution are therefore ideal candidates for novel lab-on-a-chip and remote manipulation applications in biomedicine, biophysics, chemistry, and condensed-matter physics. However, submerged graphite is not known to be amenable to magnetic manipulation, the optimal manipulation method for such applications. Here, we exploit the diamagnetism of graphite and demonstrate contactless magnetic positioning control of graphitic microflakes in diamagnetic aqueous solutions. We develop a theoretical model for magnetic manipulation of graphite microflakes and demonstrate experimentally magnetic transport of such particles over distances [Formula: see text] with peak velocities [Formula: see text] in inhomogeneous magnetic fields. We achieve fully biocompatible transport for lipid-coated graphite in NaCl aqueous solution, paving the way for previously undiscovered biomedical applications. Our results prove that micrometer-sized graphite can be magnetically manipulated in liquid media.
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Affiliation(s)
- Johnny Nguyen
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Dario Valter Conca
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Johannes Stein
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Laura Bovo
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
- London Centre for Nanotechnology, University College London, London WC1H 0AJ, United Kingdom
- Department of Innovation and Enterprise, University College London, London W1T 4TJ, United Kingdom
| | - Chris A Howard
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Isabel Llorente Garcia
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom;
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13
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Olenych IB, Aksimentyeva OI, Monastyrskii LS, Horbenko YY, Partyka MV. Electrical and Photoelectrical Properties of Reduced Graphene Oxide-Porous Silicon Nanostructures. NANOSCALE RESEARCH LETTERS 2017; 12:272. [PMID: 28410550 PMCID: PMC5391343 DOI: 10.1186/s11671-017-2043-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 04/04/2017] [Indexed: 05/20/2023]
Abstract
In this work, the hybrid structures were created by electrochemical etching of silicon wafer and deposition of reduced graphene oxide (RGO) on the porous silicon (PS) layer. With the help of SEM and AFM, the formation of hybrid PS-RGO structure was confirmed. By means of current-voltage characteristic analysis and impedance spectroscopy, we studied electrical characteristics of PS-RGO structures. The formation of photosensitive electrical barriers in hybrid structures was revealed. Temporal parameters and spectral characteristics of photoresponse in the 400-1100-nm wavelength range were investigated. The widening of spectral range of photosensitivity of the hybrid structures in short-wavelength range in comparison with single-crystal silicon was revealed. The obtained results broaden the prospects of application of the PS-RGO structures in photoelectronics.
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Affiliation(s)
- Igor B. Olenych
- Department of Electronics and Computer Technologies (Сhair of Radioelectronics and Computer Systems), Ivan Franko National University of Lviv, 50 Dragomanov Street, 79005 Lviv, Ukraine
| | - Olena I. Aksimentyeva
- Physical and Colloidal Chemistry Department, Ivan Franko National University of Lviv, 6 Kyrylo and Mefodiy Street, 79005 Lviv, Ukraine
| | - Liubomyr S. Monastyrskii
- Department of Electronics and Computer Technologies (Сhair of Radioelectronics and Computer Systems), Ivan Franko National University of Lviv, 50 Dragomanov Street, 79005 Lviv, Ukraine
| | - Yulia Yu. Horbenko
- Physical and Colloidal Chemistry Department, Ivan Franko National University of Lviv, 6 Kyrylo and Mefodiy Street, 79005 Lviv, Ukraine
| | - Maryan V. Partyka
- Solid State Physics Department, Ivan Franko National University of Lviv, 50 Dragomanov Street, 79005 Lviv, Ukraine
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14
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Olenych IB, Aksimentyeva OI, Monastyrskii LS, Horbenko YY, Partyka MV, Luchechko AP, Yarytska LI. Effect of Graphene Oxide on the Properties of Porous Silicon. NANOSCALE RESEARCH LETTERS 2016; 11:43. [PMID: 26831681 PMCID: PMC4735084 DOI: 10.1186/s11671-016-1264-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/19/2016] [Indexed: 05/29/2023]
Abstract
We studied an effect of the graphene oxide (GO) layer on the optical and electrical properties of porous silicon (PS) in hybrid PS-GO structure created by electrochemical etching of silicon wafer and deposition of GO from water dispersion on PS. With the help of scanning electron microscopy (SEM), atomic-force microscopy (AFM), and Fourier transform infrared (FTIR) spectroscopy, it was established that GO formed a thin film on the PS surface and is partly embedded in the pores of PS. A comparative analysis of the FTIR spectra for the PS and PS-GO structures confirms the passivation of the PS surface by the GO film. This film has a sufficient transparency for excitation and emission of photoluminescence (PL). Moreover, GO modifies PL spectrum of PS, shifting the PL maximum by 25 nm towards lower energies. GO deposition on the surface of the porous silicon leads to the change in the electrical parameters of PS in AC and DC modes. By means of current-voltage characteristics (CVC) and impedance spectroscopy, it is shown that the impact of GO on electrical characteristics of PS manifests in reduced capacitance and lower internal resistance of hybrid structures.
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Affiliation(s)
- Igor B Olenych
- Radioelectronics and Computer Systems Department, Ivan Franko National University of Lviv, 50 Dragomanov Street, 79005, Lviv, Ukraine.
| | - Olena I Aksimentyeva
- Physical and Colloidal Chemistry Department, Ivan Franko National University of Lviv, 6 Kyrylo and Mefodiy Street, 79005, Lviv, Ukraine.
| | - Liubomyr S Monastyrskii
- Radioelectronics and Computer Systems Department, Ivan Franko National University of Lviv, 50 Dragomanov Street, 79005, Lviv, Ukraine.
| | - Yulia Yu Horbenko
- Physical and Colloidal Chemistry Department, Ivan Franko National University of Lviv, 6 Kyrylo and Mefodiy Street, 79005, Lviv, Ukraine.
| | - Maryan V Partyka
- Solid State Physics Department, Ivan Franko National University of Lviv, 50 Dragomanov Street, 79005, Lviv, Ukraine.
| | - Andriy P Luchechko
- Electronics Department, Ivan Franko National University of Lviv, 107 Tarnavskyi Street, 79017, Lviv, Ukraine.
| | - Lidia I Yarytska
- Thermodynamics and Physics Department, Lviv State University of Live Safety, 35 Kleparivska Street, 79000, Lviv, Ukraine.
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15
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Kaplas T, Kuzhir P. Ultra-thin Graphitic Film: Synthesis and Physical Properties. NANOSCALE RESEARCH LETTERS 2016; 11:54. [PMID: 26831692 PMCID: PMC4735086 DOI: 10.1186/s11671-016-1283-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 01/26/2016] [Indexed: 06/05/2023]
Abstract
A scalable technique of chemical vapor deposition (CVD) growth of ultra-thin graphitic film is proposed. Ultra-thin graphitic films grown by a one-step CVD process on catalytic copper substrate have higher crystallinity than pyrolytic carbon grown on a non-catalytic surface and appear to be more robust than a graphene monolayer. The obtained graphitic material, not thicker than 8 nm, survives during the transfer process from a Cu substrate without a template polymer layer, typically used in the graphene transfer process to protect graphene. This makes the transfer process much more simple and cost-effective. Having electrical and optical properties compatible with what was observed for a few layers of CVD graphene, the proposed ultra-thin graphitic film offers new avenues for implementing 2D materials in real-world devices.
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Affiliation(s)
- Tommi Kaplas
- Institute of Photonics, University of Eastern Finland, Yliopistokatu 7, 80101, Joensuu, Finland
| | - Polina Kuzhir
- Research Institute for Nuclear Problems, 11 Bobrujskaya Str., Minsk, 220030, Belarus.
- Ryazan State Radio Engineering University, 59/1 Gagarina Street, Ryazan, 390005, Russia.
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16
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Lähnemann J, Flissikowski T, Wölz M, Geelhaar L, Grahn HT, Brandt O, Jahn U. Quenching of the luminescence intensity of GaN nanowires under electron beam exposure: impact of C adsorption on the exciton lifetime. NANOTECHNOLOGY 2016; 27:455706. [PMID: 27713184 DOI: 10.1088/0957-4484/27/45/455706] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electron irradiation of GaN nanowires in a scanning electron microscope strongly reduces their luminous efficiency as shown by cathodoluminescence imaging and spectroscopy. We demonstrate that this luminescence quenching originates from a combination of charge trapping at already existing surface states and the formation of new surface states induced by the adsorption of C on the nanowire sidewalls. The interplay of these effects leads to a complex temporal evolution of the quenching, which strongly depends on the incident electron dose per area. Time-resolved photoluminescence measurements on electron-irradiated samples reveal that the carbonaceous adlayer affects both the nonradiative and the radiative recombination dynamics.
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