Periodic Resonance Excitation and Intertube Interaction from Quasicontinuous Distributed Helicities in Single-Wall Carbon Nanotubes

Milnera, M.; Kürti, J.; Hulman, Martin; Kuzmany, H.

doi:10.1103/physrevlett.84.1324

Cited by 222 publications

(176 citation statements)

References 15 publications

Supporting

Mentioning

158

Contrasting

Unclassified

Order By: Relevance

“…These parameters and the values ␣ = 223.5 cm −1 and ␤ = 12.5 cm −1 have been successfully applied for describing resonant Raman spectra of SWNTs. [44][45][46] The RBM for different samples were obtained by Lorentzian or an appropriate sum of Lorentzian fittings of the breathing modes of Raman lines. We consider that only nanotubes with resonant energy window ͑E laser ± 0.1 eV͒ have a high probability for giving a strong signal in the Raman measurements.…”

Section: Raman Studiesmentioning

confidence: 99%

Evolution of catalyst particle size during carbon single walled nanotube growth and its effect on the tube characteristics

Harutyunyan

Tokune

Mora

et al. 2006

Journal of Applied Physics

View full text Add to dashboard Cite

A series of Fe catalysts, with different mean diameters, supported on alumina with different molar ratios, was studied before and after carbon single walled nanotubes growth using magnetic measurements and Raman scattering techniques (laser excitation wavelengths from 1.17to2.54eV) to follow changes on catalyst particle size and composition, as well as the relationship between particle size and diameter of nanotubes grown. In all cases, an increase and redistribution of the particle size after the growth was concluded based on the blocking temperature values and Langevin function analysis. This is explained in terms of agglomeration of particles due to carbon-induced liquefaction accompanied with an increase in the catalyst mobility. For large particles no direct correlation between the catalyst size and the nanotube diameters was observed.

show abstract

Section: Raman Studiesmentioning

confidence: 99%

Evolution of catalyst particle size during carbon single walled nanotube growth and its effect on the tube characteristics

Harutyunyan

Tokune

Mora

et al. 2006

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…A recent report on tunelling measurements in bilayer graphene 14 has found 1.07 x 10 6 ms −1 while the results above and the cyclotron absorption by Jiang et al 9 on monolayer graphene 3 give values of ≃1.1 x 10 6 ms −1 . By contrast estimates based on the electronic properties of semiconducting carbon nanotubes deduce c * K = 0.94 x 10 6 ms −1 corresponding to values of γ 0 , the transfer integral, of order 2.9 eV 15,16 .…”

mentioning

confidence: 99%

Cyclotron resonance study of the electron and hole velocity in graphene monolayers

et al. 2007

View full text Add to dashboard Cite

We report studies of cyclotron resonance in monolayer graphene. Cyclotron resonance is detected using the photoconductive response of the sample for several different Landau level occupancies. The experiments measure an electron velocity at the K-(Dirac) point of c * K = 1.093 x 10 6 ms −1 which is substantially larger than in thicker graphitic systems. In addition we observe a significant asymmetry between the electron and hole bands, leading to a difference in the electron and hole velocities of 5% by energies of 125 meV away from the Dirac point. The observation of two dimensional electronic systems in monolayer graphene 1 , where the electrons behave as Dirac Fermions and show a variety of novel quantum Hall effects 2 , 3 , 4 , has led to an explosion of interest in this system. As well as new basic science, the exceptionally high electron velocities also mean that graphene has considerable potential for applications in high speed electronics 5 . The basis for this behaviour is the nearly linear dispersion of the energy bands close to the K point, where the dispersion relations cross with the form E = ±c * h k, where c * is the electron velocity. This has been predicted for over 50 years 6 , but has only been measured recently for bulk graphite 7 and ultrathin graphite layers 8 , while the first direct absorption measurements for monolayer graphene have just been reported 9 . We describe here a photoconuctance study of cyclotron resonance in a monolayer of graphene in which the application of a magnetic field leads to the formation of Landau levels given by 10where |N | is the Landau quantum index and B is the magnetic field. This allows us to make a precise measurement of the electron velocity and to examine deviations from exact linear behaviour which show that the electron and hole-like parts of the band structure have significantly different masses and that the velocity is significantly larger than for thicker graphitic material. The experiment studies the photoconductive response from a multiply contacted single monolayer sample of graphene, which was prepared using the techniques which have been described earlier 1,2 . The graphene films were deposited by micromechanical cleavage of graphite with multi-terminal devices produced by conventional microfabrication, with a typical sample displayed in figure 1 (a). Shubnikov-de Haas oscillations were first studied at 1.5K to establish the carrier densities as a function of gate voltage and to ensure that the film studied was a single monolayer of graphene, since bilayers and thicker films are known to have a completely different dispersion relation 11 , 12 , 13 . Cyclotron resonance was measured by detecting the modulation of the conductivity of the samples produced by chopped infrared radiation from a CO 2 laser operating between 9.2 and 10.8 µm. The sample was illuminated normally with unpolarized light parallel to the magnetic field in the Faraday geometry. Typical power densities were ∼3 x 10 4 Wm −2 , corresponding to a total power incident on the sampl...

show abstract

“…This result indicates that the tubes are surrounded by the lowest environmental dielectric constant ( env ! 1) reported in the literature [1,3,4,[15][16][17][18][19][20][21]. (iii) The previously elusive high energy [18][19][20] can be observed for metallic SWNTs in these samples [14], indicating the lowest degree of perturbation for metallic tubes as compared to other samples in the literature.…”

mentioning

confidence: 72%

mentioning

confidence: 99%

Diameter Dependence of Dielectric Constant for the Excitonic Transition Energy of Single-Wall Carbon Nanotubes

Araújo¹,

Jório²,

Dresselhaus³

et al. 2010

AIP Conference Proceedings

View full text Add to dashboard Cite

The measured optical transition energies E ii of single-wall carbon nanotubes are compared with bright exciton energy calculations. The E ii differences between experiment and theory are minimized by considering a diameter-dependent dielectric constant , which comprises the screening from the tube and from the environment. Different dependencies are obtained for (E S 11 , E S 22 , E M 11 ) relative to (E S 33 , E S 44 ). A changing environment changes the diameter dependence for (E S 11 , E S 22 , E M 11 ), but for (E S 33 , E S 44 ) the environmental effects are minimal. The resulting calculated exciton energies reproduce experimental E ii values within AE70 meV for a diameter range (0:7 < d t < 3:8 nm) and 1:2 < E ii < 2:7 eV, thus providing a theoretical justification for E ii , environmental effects and important insights on the dielectric screening in one-dimensional structures. DOI: 10.1103/PhysRevLett.103.146802 PACS numbers: 73.22.Àf, 61.48.De, 78.20.-e, 78.67.Ch The last decade has been marked by an impressive development in understanding the nature of the optical transition energies in quasi-one-dimensional single-wall carbon nanotubes (SWNTs) [1], called E ii , where i ¼ 1; 2; 3; . . . denotes the intersubband transitions between the ith valence and the ith conduction band for a given SWNT. While the interest in excitons and dielectric screening in one-dimensional structures dates from research in -conjugated polymers, in carbon nanotubes the large attention started in 2003 with the so-called ''ratio problem'' [2]. Strong debate still exists about the strength of the exciton binding energy, mostly related to the complex dielectric screening in one-dimensional materials. In 2007, Araujo et al. [3] and Michel et al. [4] showed that the scaling law for the exciton energies explaining the ratio problem [2] breaks down for transitions higher than E M 11 . These results lead to the discussion of the exciton nature for higher energy levels, where quantum-chemistry calculations and solid-state physics (tight binding and firstprinciples) calculations give contradictory pictures [3,5]. Now, the accumulated knowledge in SWNTs, both theoretical and experimental [1], makes it possible to evaluate in detail the dielectric screening in one-dimensional systems.The E ii values are now understood in terms of the bright exciton energy in a framework of a tight binding calculation which includes curvature optimization [1] and manybody effects [1,5,6]. The assignment of E ii for SWNTs over a large region of both diameter (0:7 < d t < 3:8 nm) and E ii (1.2-2.7 eV) values and for a variety of surrounding materials are now available [1], thus making it possible to accurately determine the effect of the general dielectric constant on E ii . By ''general'' we mean comprises the screening from the tube and from the environment. In this work we show a d t -dependent effective values for the exciton calculation that are needed to reproduce the experimental E ii values consistently. The results thus obtained are important for...

show abstract

Periodic Resonance Excitation and Intertube Interaction from Quasicontinuous Distributed Helicities in Single-Wall Carbon Nanotubes

Cited by 222 publications

References 15 publications

Evolution of catalyst particle size during carbon single walled nanotube growth and its effect on the tube characteristics

Evolution of catalyst particle size during carbon single walled nanotube growth and its effect on the tube characteristics

Cyclotron resonance study of the electron and hole velocity in graphene monolayers

Diameter Dependence of Dielectric Constant for the Excitonic Transition Energy of Single-Wall Carbon Nanotubes

Contact Info

Product

Resources

About