Figure 2.

(a) Random walk simulations for particles trapped between non-sticky parallel plates separated by 4 µm, diffusing with bulk diffusivity D=1.0 µm²/ms. Different curves represent different time intervals, which can be associated with durations of the pulses in NMR measurements. The distributions of the positions of the center of mass are shown at the top. The average effective force exerted on the diffusing particles plotted vs. the trajectories’ center of mass (bottom). (b) The simulations were repeated by introducing surface adsorption effect so that the particles spend, on average, 25% of the time stuck at the walls.