Dielectric function of single-wall carbon nanotubes

The optical dielectric function for a bundle of aligned single-wall carbon nanotubes (SWCNs) with randomly distributed diameters has been calculated i n the one-electron approximation. It is shown that the superposition of the spectral lines corresponding to the interband transitions in SWCNs of diff erent sizes results in a strong broadening, intensity decrease, and red (re spectively, blue) shift of the resonant peak in the spectrum of the real (r espectively, imaginary) part of the response function. The implication of t he findings for understanding the optical properties of realistic SWCN samp les is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.