Test of the diffusing-diffusivity mechanism using near-wall colloidal dynamics.

Matse, Mpumelelo; Chubynsky, Mykyta V; Bechhoefer, John · Phys Rev E · 2017

basic_science · Level V

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Abstract

The mechanism of diffusing diffusivity predicts that, in environments where the diffusivity changes gradually, the displacement distribution becomes non-Gaussian, even though the mean-square displacement grows linearly with time. Here, we report single-particle tracking measurements of the diffusion of colloidal spheres near a planar substrate. Because the local effective diffusivity is known, we have been able to carry out a direct test of this mechanism for diffusion in inhomogeneous media.