Fig. 8.

Effect of different types of confinement on the diffusion of a tracer particle (R = 2 nm) in 2D and subsequent analysis of its motion in terms of the diagonal diffusion tensor components (dotted lines <∆x∆x>, solid lines <∆y∆y>) for the cases of weak repulsive saw tooth (blue) and weak attractive saw tooth (black) intermolecular potentials operating between tracer and confining elements. Top panel Diffusion of tracer particle in a cage of diameter 20 nm and anomalous characteristic flattening of the MSD plot. Central panel Diffusion of tracer particle in a channel bounded in the x direction (width 10 nm) but unbounded in the y direction. Characteristic anomalous flattening of the MSD plot for the x component but ‘normal’ behaviour shown by the y component (with repulsive potential case, indicating greater diffusion rate in both y and x directions than attractive potential case). Bottom panel Diffusion of tracer particle in a sector shaped channel (angle =30°) unbounded in the positive x direction