Diffusion of Nanocars on an Air–Glass Interface

Abstract

At room temperature, four-adamantane-wheeled nanocars thermally diffuse on an air–glass interface. A line-scan imaging method was developed to improve the time resolution in tracking their surface movement. The fast imaging technique disclosed that the four-wheeled nanocars diffuse on glass surfaces in a quasi-random two-dimensional (2D) diffusion manner. That is, they have a high tendency to keep a linear diffusion trajectory at a short time scale, which is consistent with the wheel-rolling mode diffusion. The nanocar molecules lose the directionality over time, indicating that other diffusion modes, e.g., pivoted movement, may also contribute to their thermal diffusion at room temperature. The characteristic linear movement time for the two types of nanocar molecules in this study was ∼1.2 s, from which the activation energy for the nanocars to pivot away from the original direction was estimated to be ∼65 kJ mol–1. Finally, it was shown that using the line-scanning method the diffusion coefficient of q...