2020-03-06 04:01:16

责任者: Jorio, A.;Fantini, C.;Pimenta, M.A.;Capaz, R.B.;Samsonidze, Ge.G.;Dresselhaus, G.;Dresselhaus, M.S.;Jiang, J.;Kobayashi, N.;Gruneis, A.;Saito, R. 单位: Dept. de Fisica, Univ. Fed. de Minas Gerais, Belo Horizonte, Brazil 来源出处: Physical Review B (Condensed Matter and Materials Physics)(Phys. Rev., B, Condens, Matter Mater. Phys. (USA)),2005/02/15,71(7):75401-1 摘要: This paper presents an accurate analysis of (i) the electronic transition energies E22S and E11M, (ii) the radial breathing mode (RBM) frequencies ωRBM, and (iii) the corresponding RBM intensities from 40 small-diameter single-wall carbon nanotubes (SWNTs) in the diameter range 0.7<dt<1.3 nm. The electronic transition energies (Eii) are initially considered from nonorthogonal tight-binding total-energy calculations. To account for dt-dependent many-body effects, a logarithmic correction, as proposed by Kane and Mele, is applied to both E22S and E11M. The remaining discrepancies between the experimental and theoretical Eii values are shown to be proportional to the chirality-dependent effective masses of electrons and holes, as obtained from the electron energy dispersion relations. Chirality dependent screening effects are also identified in metallic SWNTs. For the RBM frequencies, a small deviation from the linear 1/dt behavior is observed, and this deviation is analyzed based on a chirality-dependent mode softening effect due to nanotube curvature. For those interested in sample characterization, the (n,m) dependence of the resonance intensities is also addressed, the experimental results being compared with theoretical predictions based on matrix elements calculations. This analysis suggests that the (7,5), (7,6), and (6,5) SWNTs are more abundant in sodium dodecyl sulfate wrapped HiPco SWNTs in aqueous solution, in agreement with results previously reported for SWNTs grown by the CoMoCAT or alcohol methods 关键词: carbon nanotubes;chirality;effective mass;Raman spectra;soft modes;tight-binding calculations;total energy;resonance Raman spectroscopy;small-diameter single-wall carbon nanotubes;electronic transition energies;radial breathing mode frequencies;nonorthogonal tight-binding total-energy calculations;dt-dependent many-body effects;logarithmic correction;chirality-dependent effective masses;electron energy dispersion relations;holes;chirality dependent screening effects;chirality dependent mode softening;nanotube curvature;matrix elements;sodium dodecyl sulfate;alcohol methods;C