Accurate Measurement of the chirality of WS2 nanotubes
We describe the structural parameters and atomic positions of a single-walled WS2 nanotube. The structure factor is calculated in detail using analytic expressions for both single-walled and multi-walled WS2 nanotubes. Zoning scheme has been developed to obtain the ratio m/n from the electron diffraction patterns. The procedure for determination of the chiral indices of both single-walled and multi-walled WS2 nanotubes and the tilt angle is illustrated in detail for either normal incidence or inclined incidence. As an example of application, the determination of the chiral indices of a five-shell WS2 nanotube were carried out and the tilt angle was obtained as 17.7°. This method developed here is useful and valid to determinate the atomic structure of WS2 nanotubes.