| 1. |
- Anoshkin, Ilya, et al.
(författare)
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Coronene Encapsulation in Single-Walled Carbon Nanotubes : Stacked Columns, Peapods, and Nanoribbons
- 2014
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Ingår i: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 15:8, s. 1660-1665
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Tidskriftsartikel (refereegranskat)abstract
- Encapsulation of coronene inside single-walled carbon nanotubes (SWNTs) was studied under various conditions. Under high vacuum, two main types of molecular encapsulation were observed by using transmission electron microscopy: coronene dimers and molecular stacking columns perpendicular or tilted (45-608) with regard to the axis of the SWNTs. A relatively small number of short nanoribbons or polymerized coronene molecular chains were observed. However, experiments performed under an argon atmosphere (0.17 MPa) revealed reactions between the coronene molecules and the formation of hydrogen-terminated graphene nanoribbons. It was also observed that the morphology of the encapsulated products depend on the diameter of the SWNTs. The experimental results are explained by using density functional theory calculations through the energies of the coronene molecules inside the SWNTs, which depend on the orientation of the molecules and the diameter of the tubes.
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| 2. |
- Anoshkin, Ilya, 1980-, et al.
(författare)
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Single walled carbon nanotube quantification method employing the Raman signal intensity
- 2017
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Ingår i: Carbon. - United Kingdom : Elsevier BV. - 0008-6223 .- 1873-3891. ; 116, s. 547-552
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Tidskriftsartikel (refereegranskat)abstract
- A new technique for measuring the number of single walled carbon nanotubes (SWCNTs) and their concentration in a carbon nanotube layer is developed in this work. It is based on the G peak intensity of the Raman spectrum, together with precise mass and optical absorbance measurements. The dependence of the number of the carbon nanotubes on the phonon scattering intensity is observed. This method opens an opportunity for the quantitative mapping of sp2 carbon atom distribution in the SWCNT layers with a resolution limited by the focused laser spot size.
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| 3. |
- Anoshkin, Ilya V., et al.
(författare)
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Freeze-Dried Carbon Nanotube Aerogels for High-Frequency Absorber Applications
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:23, s. 19806-19811
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Tidskriftsartikel (refereegranskat)abstract
- A novel technique for millimeter wave absorber material embedded in a metal waveguide is proposed. The absorber material is a highly porous carbon nanotube (CNT) aerogel prepared by a freeze-drying technique. CNT aerogel structures are shown to be good absorbers with a low reflection coefficient, less than -12 dB at 95 GHz. The reflection coefficient of the novel absorber is 3-4 times lower than that of commercial absorbers with identical geometry. Samples prepared by freeze-drying at -25 degrees C demonstrate resonance behavior, while those prepared at liquid nitrogen temperature (-196 degrees C) exhibit a significant decrease in reflection coefficient, with no resonant behavior. CNT absorbers of identical volume based on wet-phase drying preparation show significantly worse performance than the CNT aerogel absorbers prepared by freeze-drying. Treatment of the freeze-dried CNT aerogel with n- and p-dopants (monoethanolamine and iodine vapors, respectively) shows remarkable improvement in the performance of the waveguide embedded absorbers, reducing the reflection coefficient by 2 dB across the band.
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| 4. |
- Chernov, Alexander I, et al.
(författare)
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Optical properties of graphene nanoribbons encapsulated in single-walled carbon nanotubes
- 2013
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 7:7, s. 6346-6353
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Tidskriftsartikel (refereegranskat)abstract
- We report the photoluminescence (PL) from graphene nanoribbons (GNRs) encapsulated in single-walled carbon nanotubes (SWCNTs). New PL spectral features originating from GNRs have been detected in the visible spectral range. PL peaks from GNRs have resonant character, and their positions depend on the ribbon geometrical structure in accordance with the theoretical predictions. GNRs were synthesized using confined polymerization and fusion of coronene molecules. GNR@SWCNTs material demonstrates a bright photoluminescence both in infrared (IR) and visible regions. The photoluminescence excitation mapping in the near-IR spectral range has revealed the geometry-dependent shifts of the SWCNT peaks (up to 11 meV in excitation and emission) after the process of polymerization of coronene molecules inside the nanotubes. This behavior has been attributed to the strain of SWCNTs induced by insertion of the coronene molecules.
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| 5. |
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| 6. |
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| 7. |
- Demchenko, P., et al.
(författare)
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Study of optical pumping influence on carbon nanotubes permittivity in THz frequency range
- 2018
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Ingår i: Journal of Physics. - : Institute of Physics Publishing.
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Konferensbidrag (refereegranskat)abstract
- Equivalent complex permittivity of carbon nanotubes (CNT) was measured with/without light illumination at the frequency range of 0.2-1 THz. It was shown that we can tune the dispersion of the CNT complex conductivity during varying of optical pumping (wavelength of 980 nm). These results mean that CNT is perspective candidate for development of THz tunable attenuators and phase shifters.
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| 8. |
- Fedotov, Pavel V., et al.
(författare)
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Optical Study of Nanotube and Coronene Composites
- 2013
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Ingår i: Journal of Nanoelectronics and Optoelectronics. - : American Scientific Publishers. - 1555-130X .- 1555-1318. ; 8:1, s. 16-22
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Forskningsöversikt (refereegranskat)abstract
- A novel nanomaterial, graphene nanoribbons encapsulated inside single-walled carbon nanotubes (GNR@SWNT), was studied by combined optical methods. This nanomaterial was found to have a bright photoluminescence both in IR and UV-Vis spectral ranges. Its spectral features have a complicated resonant structure different from the features of initial components: coronene molecules and SWNTs. The encapsulation ability appears to correlate strongly with the geometry of SWNTs. A weak interaction between nanotube walls and encapsulated species has been discovered: no evidence of charge or energy transfer has been registered.
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| 9. |
- Gomon, D., et al.
(författare)
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Opticaly tunable conductivity of carbon nanotubes in terahertz frequency range
- 2018
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Ingår i: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781943580460
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Konferensbidrag (refereegranskat)abstract
- Impact of infrared radiation illumination (980 nm) on the properties of carbon nanotubes (CNT), such as complex conductivity and permittivity, with different geometric parameters in the frequency range of 0.2-1.0 THz was studied.
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| 10. |
- Gorkina, Alexandra L, et al.
(författare)
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Transparent and conductive hybrid graphene/carbon nanotube films
- 2016
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Ingår i: Carbon. - : Elsevier. - 0008-6223 .- 1873-3891. ; 100, s. 501-507
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanomaterials (carbon nanotubes (CNTs) and graphene) are promising materials for optoelectronic applications, including flexible transparent and conductive films (TCFs) due to their extraordinary electrical, optical and mechanical properties. However, the performance of CNT- or graphene-only TCFs still needs to be improved. One way to enhance the optoelectrical properties of TCFs is to hybridize CNTs and graphene. This approach leads to creation of a novel material that exhibits better properties than its individual constituents. In this work, the novel hybrid CNT-graphene nanomaterial was fabricated by graphene oxide deposition on top of CNT films. The graphene oxide was then reduced by thermal annealing at ambient atmosphere or in H2 atmosphere. At the final step the CNT-graphene hybrids were chemically doped using gold(III) chloride. As a result, we show that the hybrids demonstrate excellent optoelectrical performance with the sheet resistance as low as 73 Ω/□ at 90% transmittance.
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