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Characterization of the Electronic Properties of Single‐Walled Carbon Nanotubes Filled with an Electron Donor—Rubidium Iodide: Multifrequency Raman and X‐ray Photoelectron Spectroscopy Studies
摘要： Single-walled carbon nanotubes (SWCNTs) with a mean diameter of 1.4 nm are filled with rubidium iodide. The filling of nanotubes is proved by high-resolution scanning transmission electron microscopy. The chemical composition of the filler is confirmed by X-ray photoelectron spectroscopy (XPS). The electronic properties of the filled SWCNTs are studied by XPS and Raman spectroscopy. The encapsulated salt leads to n-doping of nanotubes. The detailed multifrequency Raman spectroscopy investigation of the alteration of Raman modes of SWCNTs upon filling is conducted. The doping-induced changes in the radial breathing mode and G-band are revealed. It is found that these changes differ for the metallic and semiconducting SWCNTs. The obtained data and revealed trends are expected to be helpful for forthcoming studies to interpret the observed changes in Raman spectra of filled metallic and semiconducting SWCNTs.
关键词： Raman spectroscopy,electronic properties,X-ray photoelectron spectroscopy,rubidium iodide,filling,single-walled carbon nanotubes
更新于2025-09-11 14:15:04
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Global alignment of solution-based single-wall carbon nanotube films via machine-vision controlled filtration
摘要： Over the past decade, substantial progress has been made in the chemical control (chiral enrichment, length sorting, handedness selectivity, and filling substance) of single-wall carbon nanotubes (SWCNTs). Recently, it was shown that large, horizontally-aligned films can be created out of post-processed SWCNT solutions. Here, we use machine-vision automation and parallelization to simultaneously produce globally-aligned SWCNT films using pressure-driven filtration. Feedback control enables filtration to occur with a constant flow rate that not only improves the nematic ordering of the SWCNT films, but also provides the ability to align a wide range of SWCNT types and on a variety of nanoporous membranes using the same filtration parameters. Using polarized optical spectroscopic techniques, we show that under standard implementation, meniscus combing produces a two-dimensional radial SWCNT alignment on one side of the film. After we flatten the meniscus through silanation, spatially-resolved nematicity maps on both sides of the SWCNT film reveal global alignment across the entire structure. From experiments changing ionic strength and membrane charging, we provide evidence that the SWCNT alignment mechanism stems from an interplay of intertube interactions and ordered membrane charging. This work opens up the possibility of creating globally-aligned SWCNT film structures for a new-generation of nanotube electronics and optical control elements.
关键词： Nematic ordering,single-wall carbon nanotubes,directional charging,1D crystals
更新于2025-09-11 14:15:04
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Carbon nanotube: Controlled synthesis determines its future; 碳纳米管: 可控制备决定未来;
摘要： Carbon nanotubes (CNTs) have received broad attention in the past decades due to their excellent physical and chemical properties and thus been regarded as a powerful candidate for future star-materials. Although various CNT products and their related applications have been demonstrated recently, their performance can hardly meet the researchers’ expectations compared with their theoretical properties. The current predicament is caused by the immature synthesis method, including the basic science and the producing technology. As the synthesis with controlled structures determines its future, this review summarizes the progress on the basic research and industrialization of CNTs in the past decades, including the fine structure control, aggregation status design and scale-up production, and further points out the way for the future development of CNTs combining with specific applications.
关键词： applications,carbon nanotubes,scale-up synthesis,structure-controlled synthesis
更新于2025-09-11 14:15:04
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Carbon-nanotube computer scaled up
摘要： Electronic devices that are based on carbon nanotubes have the potential to be more energy efficient than their silicon counterparts, but have been restricted in functionality. This limitation has now been overcome. See Article p.595
关键词： microelectronic devices,silicon transistors,PMOS,CMOS technology,carbon nanotubes,NMOS
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Yb:KLuW Channel Waveguide Lasers Passively Q-Switched by Evanescent-Field Interaction with Carbon Nanotubes
摘要： Highly efficient and compact pulsed laser sources have tremendous potential for integrated photonic devices in numerous applications including spectroscopy, metrology and microscopy. Yb3+-doped monoclinic double-tungstate crystals exhibit broad and large absorption and emission cross-sections and extremely low quantum defects. Channel waveguide structures have been actively studied for miniaturization of laser systems and efficient fundamental-mode laser operation with low lasing thresholds. One of the powerful methods to fabricate waveguide structures in a transparent material is the femtosecond direct laser writing (fs-DLW). Recently, pulsed waveguide lasers utilizing saturable absorbers (SAs) have been demonstrated with SESAM and low-dimensional carbon nanostructures. [1-3] Intrinsic characteristics such as ultrafast response, broadband nonlinear absorption and flexibility for integration make single-walled carbon nanotubes (SWCNTs) and graphene unique for various types of pulsed lasers. Placing a SA between the waveguide and the laser mirror results in additional intracavity losses and Q-switching instabilities due to thermal loads through direct-field interaction with the SA. Therefore, the damage-free coupling and the potential of a monolithic design including SAs in compact lasers are highly desired. Here we demonstrate the first Q-switched operation of the Yb-doped channel waveguides based on evanescent-field interaction with SWCNTs and compare with a direct-field interaction scheme. A surface circular cladding waveguide with a vertical width of 50 μm is inscribed in the 5 at.% Yb3+-doped KLu(WO4)2 crystal by fs-DLW (employing 120-fs / 65-nJ / 1-kHz pulses at a wavelength of 795 nm). Arc-discharged SWCNTs are spin-coated on top of the Yb:KLuW waveguide or on output couplers. A 982-nm tapered amplifier diode is used as the pump source. The polarization and power of the pump beam are controlled by a polarizer and two λ/2 wave plates. The 2.88-mm-long laser cavity consists of the Yb:KLuW channel waveguide and two mirrors directly attached to both end facets of the waveguide for two interaction schemes with SWCNTs, as shown in Fig. 1(a).
关键词： Channel Waveguide Lasers,Q-switched,Yb:KLuW,Evanescent-field Interaction,Carbon Nanotubes
更新于2025-09-11 14:15:04
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Optical properties of chiral single-walled carbon nanotubes thin films
摘要： This work contains experimental results of optical properties for thin films containing Single-Walled Carbon Nanotubes. Thin films concerning 0.5, 1 and 2 mg of low dimension chiral (10,6) Single-Walled Carbon Nanotubes dispersed in low concentration aqueous sodium dodecyl sulfate solution (2 mL) were successfully fabricated by spin-coating technique on transparent substrates at ambient atmosphere. Optical properties of these thin films were examined using Transmission, Raman and Photoluminescence Spectroscopies. We find that investigated chiral Single-Walled Carbon Nanotubes show transmission and emission bands not only in infrared range but also ultraviolet and visible range.
关键词： Absorbance,Single-walled carbon nanotubes,Raman spectra,Photoluminescence,Decay time of photoluminescence,Quantum yield
更新于2025-09-11 14:15:04
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Additional obstacles in carbon nanotube growth by gas-flow directed chemical vapour deposition unveiled through improving growth density
摘要： Here, we demonstrate an approach of increasing the density of ultralong carbon nanotubes (CNTs) growth by combining fast-heating method developed by Huang et al. (J. Am. Chem. Soc., 2003, 125, 5636–5637) with catalyst support engineering. Specifically, using graphene oxide as a catalyst support for iron oxide (Fe3O4) catalyst nanoparticles, we achieved high density growth of CNTs grown by the “kite-mechanism”. Our analysis revealed that the fast-heating method reduced undesired aggregation of the catalyst nanoparticles, which has been reported to be a primary limiation mechanism, by shortening the time between substrate heating and CNT growth. In addition, the use of graphene oxide support worked to controllably and uniformly disperse catalyst nanoparticles in relatively high density which provided increased process control by extending the time before the onset of catalyst aggregation. Together, these approaches suppressed the aggregation of the catalyst nanoparticles, which facilitated the “tip-growth” mode instead of “root-growth” mode, and led to the high density growth of ultralong CNTs. Our results also indicate additional limitations and complexities on the high density CNT growth by the kite-growth approach, which limit high density synthesis.
关键词： graphene oxide,catalyst support engineering,fast-heating method,carbon nanotubes,chemical vapour deposition
更新于2025-09-11 14:15:04
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Multifunctional Effect of <i>p</i> ‐Doping, Antireflection, and Encapsulation by Polymeric Acid for High Efficiency and Stable Carbon Nanotube‐Based Silicon Solar Cells
摘要： Silicon solar cells among different types of solar energy harvesters have entered the commercial market owing to their high power conversion efficiency and stability. By replacing the electrode and the p-type layer by a single layer of carbon nanotubes, the device can be further simplified. This greatly augments the attractiveness of silicon solar cells in the light of raw material shortages and the solar payback period, as well as lowering the fabrication costs. However, carbon nanotube-based silicon solar cells still lack device efficiency and stability. These can be improved by chemical doping, antireflection coating, and encapsulation. In this work, the multifunctional effects of p-doping, antireflection, and encapsulation are observed simultaneously, by applying a polymeric acid. This method increases the power conversion efficiency of single-walled carbon nanotube-based silicon solar cells from 9.5% to 14.4% and leads to unprecedented device stability of more than 120 d under severe conditions. In addition, the polymeric acid-applied carbon nanotube-based silicon solar cells show excellent chemical and mechanical robustness. The obtained stable efficiency stands the highest among the reported carbon nanotube-based silicon solar cells.
关键词： doping,carbon nanotubes,silicon solar cells,antireflection,Nafion
更新于2025-09-11 14:15:04
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Neutron Activated <sup>153</sup> Sm Sealed in Carbon Nanocapsules for <i>In Vivo</i> Imaging and Tumor Radiotherapy
摘要： Radiation therapy along with chemotherapy and surgery remain the main cancer treatments. Radiotherapy can be applied to patients externally (external beam radiotherapy) or internally (brachytherapy and radioisotope therapy). Previously, nanoencapsulation of radioactive crystals within carbon nanotubes, followed by end-closing, resulted in the formation of nanocapsules that allowed ultrasensitive imaging in healthy mice. Herein we report on the preparation of nanocapsules initially sealing ‘cold’ isotopically enriched samarium (152Sm), which can then be activated on demand to their ‘hot’ radioactive form (153Sm) by neutron irradiation. The use of ‘cold’ isotopes avoids the need for radioactive facilities during the preparation of the nanocapsules, reduces radiation exposure to personnel, prevents the generation of nuclear waste and evades the time constraints imposed by the decay of radionuclides. A very high specific radioactivity is achieved by neutron irradiation (up to 11.37 GBq/mg), making the ‘hot’ nanocapsules useful not only for in vivo imaging but also therapeutically effective against lung cancer metastases after intravenous injection. The high in vivo stability of the radioactive payload, selective toxicity to cancerous tissues and the elegant preparation method offer a paradigm for application of nanomaterials in radiotherapy.
关键词： nuclear imaging,filled carbon nanotubes,nanoencapsulation,nanooncology,radiooncology,cancer therapy
更新于2025-09-11 14:15:04
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Nonlinear mixing of lasers and terahertz generation on CNT embedded metal surface
摘要： A scheme of terahertz generation, employing carbon nanotubes (CNTs) embedded metal surface is proposed. The surface is irradiated by two laser beams at angle of incidence θ. The lasers exert a ponderomotive force on CNT electrons at the beat frequency ω=ω1-ω2 and produce a nonlinear current, turning the nanotubes into an array of antennae emitting beat frequency THz radiation. The THz ?eld is resonantly enhanced at the plasmon resonance, =ω ω β/2 p , where ωp is the plasma frequency of the CNT electrons and β is a parameter that characterizes the metallic susceptibility of the CNTs. The collisions are a limiting factor and cause heating of CNTs.
关键词： Terahertz generation,Carbon nanotubes,Ponderomotive force,Nonlinear mixing
更新于2025-09-11 14:15:04