Raman spectra were performed on the double-walled carbon nanotubes (DWNTs) at different E-laser of excitation. The interlayer distance of the DWNTs calculated from radial breathing mode (RBM) varies from 0.335 to 0.42 nm. The D-band of the carbon nanotubes can be expressed as omega(D) = omega(0) + 26.5E(laser), where omega(0) is about 1260 cm(-1) for DWNTs, 1270 cm(-1) for single-walled carbon nanotubes (SWNTs) and 1285 cm(-1) for multi-walled carbon nanotubes (MWNTs), respectively. (C) 2003 Elsevier B.V. All rights reserved.