Diffusion of colloids in one-dimensional light channels

Abstract

Single-file diffusion (SFD), prevalent in many chemical and biological processes, refers to the one-dimensional motion of interacting particles in pores which are so narrow that the mutual passage of particles is excluded. Since the sequence of particles in such a situation remains unaffected over time t, this leads to strong deviations from normal diffusion, e.g. an increase of the particle mean-square-displacement as the square root of t. We present experimental results of the diffusive behaviour of colloidal particles in one-dimensional channels with varying particle density. The channels are realized by means of a scanning optical tweezers. Based on a new analytical approach (Kollmann 2003 Phys. Rev. Lett. 90 180602) for SFD, we can predict quantitatively the long-time, diffusive behaviour from the short time density fluctuations in our systems.

Diffusion in quasi-one-dimensional channels: A small system n, p, T, transition state theory for hopping times

“…However, the observation of SFD by NMR is subject to some uncertainty in systems where alternative diffusion mechanisms could be responsible [23,24]. Single file diffusion has also been observed in colloidal systems [25,26], where it is being used in nano-and micro-fluidic devices [27,28], as well as to control flow rates in the delivery of drugs [29].…”

Single-file diffusion of particles with long-range interactions: Damping and finite-size effects

“…This phenomenon called Single File Diffusion was first noticed in 1955 by Hodgkin and Keynes [1] who were studying water transport through molecular-sized channels in biological membranes. Since then, SFD also appeared in the diffusion of molecules in porous materials like zeolites [2][3][4], of charges along polymer chains [5], of ions in electrostatic traps [6], of vortices in band superconductors [7,8] and of colloids in nanosized structures [9][10][11][12][13][14] or optically generated channels [15,16]. Even though SFD can be encountered in a lot of various physical systems, most of the theoretical studies devoted to it are generally restricted to the simplest case : an infinite overdamped system with hard core interactions.…”

“…This is the initial assumption in the existing models for long range interacting particles [22,23]. The relevant experiments were generally done with solutions of colloïds [9][10][11][12][13][14][15][16] for which overdamping is a safe assumption. The simulations [26,27] are shown in [24] to be in good agreement with the theoretical prediction of Kollmann, but they also assume overdamping in the choice of the simulation algorithm.…”

Spreading in narrow channels

“…[25,26,27,28,29,30,31,32,33,34]). Such systems show the interesting feature of non-diffusive behavior of tracer particles, which stimulated experimental (see, e.g., Refs.…”