Anomalous diffusion and power-law relaxation of the time averaged mean squared displacement in worm-like micellar solutions

By Jae-Hyung Jeon, N. Leijnse, L. Oddershede, Ralf Metzler. 2013

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We report the results of single tracer particle tracking by optical tweezers and video microscopy in micellar solutions. From careful analysis in terms of different stochastic models, we show that the polystyrene tracer beads of size 0.52–2.5 μm after short-time normal diffusion turn over to perform anomalous diffusion of the form 〈r2(t)〉 ≃ tα with α ≈ 0.3. This free anomalous diffusion is ergodic and consistent with a description in terms of the generalized Langevin equation with a power-law memory kernel. With optical tweezers tracking, we unveil a power-law relaxation over several decades in time to the thermal plateau value under the confinement of the harmonic tweezer potential, as predicted previously (Phys. Rev. E 85 021147 (2012)). After the subdiffusive motion in the millisecond range, the motion becomes faster and turns either back to normal Brownian diffusion or to even faster superdiffusion, depending on the size of the tracer beads.

Subfields: Atomic and Molecular Physics, and Optics, Modeling and Simulation, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/7426c4b7297f8cefa1e648995aa6462767af1a08