Diameter dependent Raman scattering of WS 2 nanotubes

The effect of the tube diameter and of the surface layer on the Raman spectra of WS 2 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 WS 2 nanostructures and not a surface layer effect.