Curvature effects on the structural, electronic and optical properties of isolated single-walled carbon nanotubes within a symmetry-adapted non-orthogonal tight-binding model

Popov, V. N.

doi:10.1088/1367-2630/6/1/017

Cited by 204 publications

(170 citation statements)

References 30 publications

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“…Their diameters, d (nm), were extracted from the frequencies of their radial breathing modes (RBMs) using the relation o RBM (cm À 1 ) ¼ 204/d þ 27 for suspended nanotubes 21,22 . Their chiral indices were subsequently identified by comparing the optical resonances with the spectral position and spacing of the different excitonic transitions predicted by Kataura plots [23][24][25] (for more details see Supplementary Note 1 and Supplementary Table S1). …”

Section: Resultsmentioning

confidence: 99%

Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes

et al. 2013

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The optical properties of single-wall carbon nanotubes are very promising for developing novel opto-electronic components and sensors with applications in many fields. Despite numerous studies performed using photoluminescence or Raman and Rayleigh scattering, knowledge of their optical response is still partial. Here we determine using spatial modulation spectroscopy, over a broad optical spectral range, the spectrum and amplitude of the absorption cross-section of individual semiconducting single-wall carbon nanotubes. These quantitative measurements permit determination of the oscillator strength of the different excitonic resonances and their dependencies on the excitonic transition and type of semiconducting nanotube. A non-resonant background is also identified and its cross-section comparable to the ideal graphene optical absorbance. Furthermore, investigation of the same single-wall nanotube either free standing or lying on a substrate shows large broadening of the excitonic resonances with increase of oscillator strength, as well as stark weakening of polarization-dependent antenna effects, due to nanotube-substrate interaction.

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Section: Resultsmentioning

confidence: 99%

Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes

et al. 2013

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“…In closing, the tight binding method provides an excellent framework for calculating and understanding the electronic properties of carbon nanotubes. To further refine the results, the calculation can be modified to include additional nearest neighbor carbon atoms and overlap integrals, 99 the effects of curvature, 100 and exciton influences (vide infra). 101,102 For example, because tight binding does not account for the curvature of the SWNT, it is only a good approximation for large diameter nanotubes (d t > 1.5 nm)…”

Section: Swnt Electronic Band Structurementioning

confidence: 99%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic molecules that have remained at the forefront of nanomaterials research since 1991, largely due to their exceptional and unusual mechanical, electrical, and optical properties. The motivation for understanding how nanotubes interact with light (i.e., SWNT photophysics) is both fundamental and applied. Individual nanotubes may someday be used as superior near-infrared fluorophores, biological tags and sensors, and components for ultrahigh-speed optical communications systems. Establishing an understanding of basic nanotube photophysics is intrinsically significant and should enable the rapid development of such innovations. Unlike conventional molecules, carbon nanotubes are synthesized as heterogeneous samples, composed of molecules with different diameters, chiralities, and lengths. Because a nanotube can be either metallic or semiconducting depending on its particular molecular structure, SWNT samples are also mixtures of conductors and semiconductors. Early progress in understanding the optical characteristics of SWNTs was limited because nanotubes aggregate when synthesized, causing a mixing of the energy states of different nanotube structures. Recently, significant improvements in sample preparation have made it possible to isolate individual nanotubes, enabling many advances in characterizing their optical properties. In this Account, single-molecule confocal microscopy and spectroscopy were implemented to study the fluorescence from individual nanotubes. Single-molecule measurements naturally circumvent the difficulties associated with SWNT sample inhomogeneities. Intrinsic SWNT photoluminescence has a simple narrow Lorentzian line shape and a polarization dependence, as expected for a one-dimensional system. Although the local environment heavily influences the optical transition wavelength and intensity, single nanotubes are exceptionally photostable. In fact, they have the unique characteristic that their single molecule fluorescence intensity remains constant over time; SWNTs do not “blink” or photobleach under ambient conditions. In addition, transient absorption spectroscopy was used to examine the relaxation dynamics of photoexcited nanotubes and to elucidate the nature of the SWNT excited state. For metallic SWNTs, very fast initial recovery times (300–500 fs) corresponded to excited-state relaxation. For semiconducting SWNTs, an additional slower decay component was observed (50–100 ps) that corresponded to electron–hole recombination. As the excitation intensity was increased, multiple electron–hole pairs were generated in the SWNT; however, these e−h pairs annihilated each other completely in under 3 ps. Studying the dynamics of this annihilation process revealed the lifetimes for one, two, and three e−h pairs, which further confirmed that the photoexcitation of SWNTs produces not free electrons but rather one-dimensional bound electron–hole pairs (i.e., excitons). In summary, nanotube photophysics is a rapidly developing area o...

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“…We have compared the dielectric response function of a single (5, 4) CNT, calculated by TB models with different levels of complexity from [59,60], with the value estimated from the above effective medium approximation. Taking into account that the TB method, in general, underestimates the experimental data by 0.3 eV, the axial component of the imaginary part of the dielectric function tensor 2zz at the transition energy E µ,µ±1 = 1.982 eV gives a value in the range n = 1.835-2.82 for the refractive index along the nanotube axis.…”

Section: Discussionmentioning

confidence: 99%

Nonlinear coherent magneto-optical response of a single chiral carbon nanotube

Slavcheva

Roussignol

2010

New J. Phys.

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View the article online for updates and enhancements. Abstract. We propose a theoretical framework and dynamical model for the description of the natural optical activity and Faraday rotation in an individual chiral single-wall carbon nanotube (CNT) in the highly nonlinear coherent regime. The model is based on a discrete-level representation of the optically active states near the band edge. Chirality is modelled by a system Hamiltonian in a four-level basis corresponding to energy-level configurations, specific for each handedness, that are mirror reflections of each other. The axial magnetic field is introduced through the Aharonov-Bohm and Zeeman energylevel shifts. The time evolution of the quantum system, describing a single nanotube with defined chirality, under an ultrashort polarized pulse excitation is studied using the coupled coherent vector Maxwell-pseudospin equations (Slavcheva 2008 Phys. Rev. B 77 115347). We provide an estimate for the effective dielectric constant and the optical dipole matrix element for transitions excited by circularly polarized light in a single nanotube and calculate the magnitude of the circular dichroism and the specific rotatory power in the absence and in the presence of an axial magnetic field. Giant natural gyrotropy (polarization rotatory power ∼3000 • mm −1 (B = 0 T)), superior to that of the crystal birefringent materials, liquid crystals and comparable or exceeding that of the artificially made helical photonic structures, is numerically demonstrated for the specific case of a (5, 4) nanotube. A quantitative estimate of the coherent nonlinear magneto-chiral optical effect in an axial magnetic field is given 3 Authors to whom any correspondence should be addressed. . The model provides a framework for the investigation of the chirality and magnetic field dependence of the ultrafast nonlinear optical response of a single CNT.

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Curvature effects on the structural, electronic and optical properties of isolated single-walled carbon nanotubes within a symmetry-adapted non-orthogonal tight-binding model

Cited by 204 publications

References 30 publications

Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes

Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes

Photophysics of Individual Single-Walled Carbon Nanotubes

Nonlinear coherent magneto-optical response of a single chiral carbon nanotube

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