The phenomenon of diffusion is omnipresent and crucial basis of many every-day processes. Diffusion plays a central role for the transport of very small particles. The investigation of Brownian motions by Einstein, Sutherland and Smoluchowski was the foundation of all further research on diffusion processes, also for Prof Peter Hänggi from the University of Augsburg.
Passing the channel
Scientists from various fields such as physics, chemistry and biology are especially interested in the transport through natural and artificial ionic channels and nanopores. Unavoidable component of all channel structures are confining boundaries. The surface of such boundaries are typically not smooth but exhibit rather complex shapes. Those structural features affect the spontaneous particle zig-zag movements, jittery Brownian motions, on a molecular level. On one hand, there are direct microparticle interactions with the environment, boundaries and surrounding fluid, of attracting and repelling nature altering the transport velocity. On the other hand, the available phase space for motions along the transport direction is limited and determines it, and therefore induces entropic effects.
Hydrodynamic effects were notoriously difficult, if not impossible to explore quantitatively, as the ubiquitous attracting and repelling interactions of corrugated surfaces are hard to model. Solely entropic effects were involved in analytical calculations although they did not mirror the system in its entirety.
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