The cluster formation of silver adatoms on carbon nanotubes was investigated in order to determine the curvature effect upon surface diffusion. By analyzing the cluster density as a function of the deposition time for various diameters of the carbon nanotubes, the scaling form was obtained for describing the curvature effect upon surface diffusion to a first-order approximation. It was found that the curvature effect upon the surface diffusion could be well described by using an inverse-power relationship between the deposition time and the scaled deposition time, where the power-law exponent characterized geometric properties of the carbon nanotubes, such as helicity. The value of the exponent for armchair-type nanotubes was larger than for the zig-zag and chiral-type carbon nanotubes. The scaling relationship was further demonstrated and verified by numerical simulations, and was explained in terms of a two-dimensional random-walk model. It was suggested that armchair-type single-wall carbon nanotubes might be identified by measuring the value of the exponent.

Curvature Effect on the Surface Diffusion of Silver Adatoms on Carbon Nanotubes: Deposition Experiments and Numerical Simulations. M.C.Wu, C.L.Li, C.K.Hu, Y.C.Chang, Y.H.Liaw, L.W.Huang, C.S.Chang, T.T.Tsong, T.Hsu: Physical Review B, 2006, 74[12], 125424