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

Jae-Hyung Joen, Natascha Leijnse, Lene Broeng Oddershede, Ralf Metzler

145 Citations (Scopus)

Abstract

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.

Original languageEnglish
JournalNew Journal of Physics
Volume15
Pages (from-to) 045011
ISSN1367-2630
DOIs
Publication statusPublished - 17 Apr 2013

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