Fig. 2. Typical snapshots and trajectories of photon-activated gold NP diffusion in liquid.
(A) Typical snapshots of a gold NP diffusion under 1-kHz laser pulse (fluence of 2.3 mJ/cm2) excitation at the different times. The NP was driven to move by rapid nucleation, expansion, detachment, and collapse of the photoinduced steam NBs near the particle surface (see the circles with white contrast). (B and C) Two typical trajectories (left column) of the gold NP diffusion and the corresponding displacement distributions along x and y (right column) at different laser fluences of 2.0 and 2.3 mJ/cm2, respectively. The dashed black lines in the right column of (B) and (C) show the Gaussian fit, which indicate that the NP translates in a manner of random walk.