Energy levels of deposited carbon nanotubes

2004 ◽  
Vol 21 (2-4) ◽  
pp. 1079-1083 ◽  
Author(s):  
R Ferreira
Keyword(s):  
Carbon Nanotubes ◽  
Energy Levels

Quantum Mechanical Investigation of Geometrical Structure and Dynamic Behavior of h-BNNT (9,9-5) and h-AlNNT (9,9-5)Single-Walled Nanotubes: NBO Analysis

2019 ◽  
Vol 16 (9) ◽  
pp. 705-717
Author(s):  
Mehrnoosh Khaleghian ◽  
Fatemeh Azarakhshi
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional ◽  
Structural Parameters ◽  
Energy Levels ◽  
Nbo Analysis ◽  
Electronic Energy ◽  
Boron Nitride Nanotubes ◽  
Basis Set ◽  
B3lyp Method ◽  
Mechanical Investigation

In the present research, B45H36N45 Born Nitride (9,9) nanotube (BNNT) and Al45H36N45 Aluminum nitride (9,9) nanotube (AlNNT) have been studied, both having the same length of 5 angstroms. The main reason for choosing boron nitride nanotubes is their interesting properties compared with carbon nanotubes. For example, resistance to oxidation at high temperatures, chemical and thermal stability higher rather than carbon nanotubes and conductivity in these nanotubes, unlike carbon nanotubes, does not depend on the type of nanotube chirality. The method used in this study is the density functional theory (DFT) at Becke3, Lee-Yang-Parr (B3LYP) method and 6-31G* basis set for all the calculations. At first, the samples were simulated and then the optimized structure was obtained using Gaussian 09 software. The structural parameters of each nanotube were determined in 5 layers. Frequency calculations in order to extract the thermodynamic parameters and natural bond orbital (NBO) calculations have been performed to evaluate the electron density and electrostatic environment of different layers, energy levels and related parameters, such as ionization energy and electronic energy, bond gap energy and the share of hybrid orbitals of different layers.

scholarly journals Spectroscopy of a rotating hydrogen molecule in carbon nanotubes

2019 ◽  
Vol 21 (7) ◽  
pp. 3423-3430 ◽  
Author(s):  
María Pilar de Lara-Castells ◽  
Alexander O. Mitrushchenkov
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Hydrogen ◽  
Hydrogen Molecule ◽  
Energy Levels

Computing the energy levels of molecular hydrogen rotating in carbon nanotubes of increasing size.

scholarly journals Assessing the Damage Tolerance of Out of Autoclave Manufactured Carbon Fibre Reinforced Polymers Modified with Multi-Walled Carbon Nanotubes

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1080 ◽  
Author(s):  
Polyxeni Dimoka ◽  
Spyridon Psarras ◽  
Christine Kostagiannakopoulou ◽  
Vassilis Kostopoulos
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Reference Material ◽  
Carbon Fibre ◽  
Damage Tolerance ◽  
Energy Levels ◽  
Multi Walled Carbon Nanotubes ◽  
Out Of Autoclave ◽  
Walled Carbon Nanotubes ◽  
The Impact

The present study aims to investigate the influence of multi-walled carbon nanotubes (MWCNTs) on the damage tolerance after impact (CAI) of the development of Out of Autoclave (OoA) carbon fibre reinforced polymer (CFRP) laminates. The introduction of MWCNTs into the structure of CFRPs has been succeeded by adding carbon nanotube-enriched sizing agent for the pre-treatment of the fibre preform and using an in-house developed methodology that can be easily scaled up. The modified CFRPs laminates with 1.5 wt.% MWCNTs were subjected to low velocity impact at three impact energy levels (8, 15 and 30 J) and directly compared with the unmodified laminates. In terms of the CFRPs impact performance, compressive strength of nanomodified composites was improved for all energy levels compared to the reference material. The test results obtained from C-scan analysis of nano-modified specimens showed that the delamination area after the impact is mainly reduced, without the degradation of compressive strength and stiffness, indicating a potential improvement of damage tolerance compared to the reference material. SEM analysis of fracture surfaces revealed the additional energy dissipation mechanisms; pulled-out carbon nanotubes which is the main reason for the improved damage tolerance of the multifunctional composites.

GENERAL OVERVIEW OVER INVESTIGATIONS ON LOW-DIMENSIONAL CARBON-BASED MATERIALS IN MAGNETIC FIELDS ABOVE 50 T

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2777-2778
Author(s):  
OLIVER PORTUGALL
Keyword(s):  
Carbon Nanotubes ◽  
Magnetic Fields ◽  
Near Infrared ◽  
Energy Levels ◽  
Experimental Investigations ◽  
Pulsed Magnetic Fields ◽  
Destructive Effect ◽  
Liquid Suspension ◽  
Low Dimensional ◽  
Absorption Measurements

Carbon nanotubes have been intensively investigated in pulsed magnetic fields, mainly to identify the effect of a magnetic flux along the tube axis on the energy band structure. Clear manifestations of the Ahoronov-Bohm effect have been observed in near-infrared absorption measurements on suspended tubes1 as well as in single-tube transport experiments.2 Subsequent studies have shed light on the excitonic nature of optical excitations3 and the magnetic-field induced optical activity of such excitons.4,5 Ongoing activities are focussing on the magnetic alignment dynamics of carbon nanotubes in liquid suspension which has the potential to provide valuable information on their magnetic susceptibility. Experimental investigations on graphene in pulsed magnetic fields are far less advanced than those on carbon nanotubes. This is due to various experimental factors such as intrinsically short integration times for optical experiments and the destructive effect of electromagnetic perturbations on insufficiently screened transport samples. First results have nevertheless been obtained in both cases: Previous absorption measurements6 up to 32 T have been extended to higher fields thereby confirming the characteristic B1/2-dependence of energy levels. Transport measurements, on the other hand, have revealed extended plateaus in the two-terminal resistance of graphene.7 In this talk we gave a complete overview over recent and ongoing experimental investigations on carbon nanotubes and graphene in magnetic fields above 50 T. We referred to the work of several international collaborations including groups from Houston, Los Alamos, Berlin, Oxford, Tokyo, Dublin, Grenoble and Toulouse. Note from Publisher: This article contains the abstract only.

scholarly journals Anisotropic Photoluminescence of Poly(3-hexyl thiophene) and Their Composites with Single-Walled Carbon Nanotubes Highly Separated in Metallic and Semiconducting Tubes

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 294
Author(s):  
Mihaela Baibarac ◽  
Grigory Arzumanyan ◽  
Monica Daescu ◽  
Adelina Udrescu ◽  
Kahramon Mamatkulov
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Interaction ◽  
Electrochemical Polymerization ◽  
Energy Levels ◽  
Single Walled Carbon Nanotubes ◽  
Single Walled Carbon ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Walled Carbon Nanotubes

In this work, the effect of the single-walled carbon nanotubes (SWNTs) as the mixtures of metallic and semiconducting tubes (M + S-SWNTs) as well as highly separated semiconducting (S-SWNTs) and metallic (M-SWNTs) tubes on the photoluminescence (PL) of poly(3-hexyl thiophene) (P3HT) was reported. Two methods were used to prepare such composites, that is, the chemical interaction of the two constituents and the electrochemical polymerization of the 3-hexyl thiophene onto the rough Au supports modified with carbon nanotubes (CNTs). The measurements of the anisotropic PL of these composites have highlighted a significant diminution of the angle of the binding of the P3HT films electrochemical synthetized onto Au electrodes covered with M + S-SWNTs. This change was attributed to metallic tubes, as was demonstrated using the anisotropic PL measurements carried out on the P3HT/M-SWNTs and P3HT/S-SWNTs composites. Small variations in the angle of the binding were reported in the case of the composites prepared by chemical interaction of the two constituents. The proposed mechanism to explain this behavior took into account the functionalization process of CNTs with P3HT. The experimental arguments of the functionalization process of CNTs with P3HT were shown by the UV-VIS-NIR and FTIR spectroscopy as well as surface-enhanced Raman scattering (SERS). A PL quenching process of P3HT induced both in the presence of S-SWNTs and M-SWNTs was reported, too. This process origins in the various de-excitation pathways which can be developed considering the energy levels diagram of the two constituents of each studied composite.

Optical and thermal stimulated luminescence in carbon nanotubes

2011 ◽  
Vol 225 (4) ◽  
pp. 145-147
Author(s):  
Jung-Chuan Fan ◽  
Huang-Huei Sung ◽  
Chun-Rong Lin
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Energy Levels ◽  
Infrared Emission ◽  
Major Peak ◽  
X Ray Diffraction ◽  
X Ray ◽  
Simple Alternative ◽  
Luminescence Measurement ◽  
Scanning Electron

The semiconductivity of carbon nanotubes has been investigated by the luminescence measurement. The nanotubes were characterized by scanning electron microscopy and X-ray diffraction. Carbon nanotubes can luminesce under laser irradiation. Using the photoluminescence measurements the emission spectrum is very wide near the infrared emission range, with a major peak at 1.3 eV. According to the temperature dependence of the photoluminescence and the thermal photoluminescence experiments, the luminescence of carbon nanotubes comes from the center of the energy trap of a defect. In view of this result, it is suggested that the technique of thermal stimulated luminescence provides a simple alternative method to obtain the energy levels in carbon nanotubes systems.

scholarly journals Recent Applications of Carbon Nanotubes in Organic Solar Cells

2022 ◽  
Vol 9 ◽  
Author(s):  
Edigar Muchuweni ◽  
Edwin T. Mombeshora ◽  
Bice S. Martincigh ◽  
Vincent O. Nyamori
Keyword(s):  
Carbon Nanotubes ◽  
Solar Cells ◽  
Organic Solar Cells ◽  
Indium Tin Oxide ◽  
Carrier Transport ◽  
Low Cost ◽  
Energy Levels ◽  
Optical Transmittance ◽  
Interpenetrating Networks ◽  
Research Attention

In recent years, carbon-based materials, particularly carbon nanotubes (CNTs), have gained intensive research attention in the fabrication of organic solar cells (OSCs) due to their outstanding physicochemical properties, low-cost, environmental friendliness and the natural abundance of carbon. In this regard, the low sheet resistance and high optical transmittance of CNTs enables their application as alternative anodes to the widely used indium tin oxide (ITO), which is toxic, expensive and scarce. Also, the synergy between the large specific surface area and high electrical conductivity of CNTs provides both large donor-acceptor interfaces and conductive interpenetrating networks for exciton dissociation and charge carrier transport. Furthermore, the facile tunability of the energy levels of CNTs provides proper energy level alignment between the active layer and electrodes for effective extraction and transportation of charge carriers. In addition, the hydrophobic nature and high thermal conductivity of CNTs enables them to form protective layers that improve the moisture and thermal stability of OSCs, thereby prolonging the devices’ lifetime. Recently, the introduction of CNTs into OSCs produced a substantial increase in efficiency from ∼0.68 to above 14.00%. Thus, further optimization of the optoelectronic properties of CNTs can conceivably help OSCs to compete with silicon solar cells that have been commercialized. Therefore, this study presents the recent breakthroughs in efficiency and stability of OSCs, achieved mainly over 2018–2021 by incorporating CNTs into electrodes, active layers and charge transport layers. The challenges, advantages and recommendations for the fabrication of low-cost, highly efficient and sustainable next-generation OSCs are also discussed, to open up avenues for commercialization.

scholarly journals Many-particle excitations in non-covalently doped single-walled carbon nanotubes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Timofei V. Eremin ◽  
Petr A. Obraztsov ◽  
Vladimir A. Velikanov ◽  
Tatiana V. Shubina ◽  
Elena D. Obraztsova
Keyword(s):  
Carbon Nanotubes ◽  
Transient Absorption ◽  
Energy State ◽  
Energy Levels ◽  
Optical Excitation ◽  
Single Walled Carbon Nanotubes ◽  
Single Walled Carbon ◽  
New Energy ◽  
Walled Carbon Nanotubes ◽  
Kinetics Of

Abstract Doping of single-walled carbon nanotubes leads to the formation of new energy levels which are able to participate in optical processes. Here, we investigate (6,5)-single walled carbon nanotubes doped in a solution of hydrochloric acid using optical absorption, photoluminescence, and pump-probe transient absorption techniques. We find that, beyond a certain level of doping, the optical spectra of such nanotubes exhibit the spectral features related to two doping-induced levels, which we assign to a localized exciton $$X$$ X and a trion T, appearing in addition to an ordinary exciton $${E}_{1}$$ E 1 . We evaluate the formation and relaxation kinetics of respective states and demonstrate that the kinetics difference between E1 and X energy levels perfectly matches the kinetics of the state T. This original finding evidences the formation of trions through nonradiative relaxation via the $$X$$ X level, rather than via a direct optical excitation from the ground energy state of nanotubes.

A Perturbation Theory for the Population of Atomic Energy Levels in Non-Lte Plasmas

1988 ◽  
Vol 102 ◽  
pp. 343-347
Author(s):  
M. Klapisch
Keyword(s):  
Perturbation Theory ◽  
Small Parameter ◽  
Classification Scheme ◽  
Sum Rules ◽  
Energy Levels ◽  
Natural Classification ◽  
Quantum Numbers ◽  
Formal Expansion ◽  
Atomic Energy Levels ◽  
As Effects

AbstractA formal expansion of the CRM in powers of a small parameter is presented. The terms of the expansion are products of matrices. Inverses are interpreted as effects of cascades.It will be shown that this allows for the separation of the different contributions to the populations, thus providing a natural classification scheme for processes involving atoms in plasmas. Sum rules can be formulated, allowing the population of the levels, in some simple cases, to be related in a transparent way to the quantum numbers.

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