Diameter dependent Raman scattering of WS2 nanotubes

The effect of the tube diameter and of the surface layer on the Raman spectra Of WS2 nanotubes is investigated. With decreasing diameter, a disorder-induced line in the A(1g) mode range, the D-A(1g) line, is selectively enhanced. This enhancement is attributed to an increasing structural disorder in smaller nanotubes. On the other hand, no significant effect on the D-A(1g)/A(1g), intensity ratio is observed for a Raman scan perpendicular to a 290 nm diameter tube. Therefore the enhancement of the disorder-induced line is an intrinsic property of WS2 nanostructures and not a surface layer effect. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim