Phonons in MoS<inf>2</inf> and WS<inf>2</inf> nanotubes

Abstract

Phonon of the single-wall MS2 (M=Mo,W) nanotubes with diameters up to 50nm are systematically calculated using the full symmetry implemented valence-force-field model. Infrared and Raman active modes are singled out by the symmetry, and their applications in the experimental sample characterization are discussed. Raman measurement of the multiwall tubes and bulk has been performed. Obtained results are interpreted by simple coupled-spring like model concerning the same symmetry modes of walls.