Figure 3: Spatio-temporal evolution of particle distributions upon exposure to CO₂.

(a,b) Experimental and (c,d) computed plots for (a,c) negatively charged (polystyrene, diameter 0.5 μm) and (b,d) positively charged particles (amine-functionalized polystyrene, diameter 1 μm) exposed to CO₂ at 136 kPa. I and n represent fluorescence intensity and particle concentration, respectively. Subscript 0 indicates a quantity at t=0 s. The experimental plots are obtained by averaging the intensity over the width of the channel. The white curves in (c,d) indicate the trajectories of individual particles obtained by integrating their diffusiophoretic velocities and neglecting Brownian motion. The computations for (d) account for the presence of a low concentration of ionic solutes in the positive particle suspensions (see Supplementary Fig. 2 and Supplementary Discussion).