Superdiffusive-like motion of colloidal nanorods

In recent experiments, the temporal average C (t) of the mean square displacement for nanorods moving through a chemical monolayer was explored. The results showed a scaling C (t) ∼ t1.6, which suggest the existence of superdiffusive motion for these particles. In this paper, we interpret these results by means of a continuous-time random walk (CTRW) model from which we can reproduce the exponent 1.6 and the curve C (t) versus time found in the experiments. We show that the behavior observed arises as a consequence of the superposition of different transport mechanisms: directional propulsion plus translational and rotational diffusion. Our model reveals that this superdiffusive-like scaling may also be found in other systems as in chemotactic biological motion, provided that the characteristic times for translational and rotational diffusions are very different. © 2009 American Institute of Physics.