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arXiv · 1402.6913

Longterm Influence of Inertia on the Diffusion of a Brownian Particle

Giuseppe Pesce·Giorgio Volpe·Giovanni Volpe·Antonio Sasso
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Abstract

We demonstrate experimentally that a Brownian particle is subject to inertial effects at long time scales. By using a blinking optical tweezers, we extend the range of previous experiments by several orders of magnitude up to a few seconds. The measured mean square displacement of a freely diffusing Brownian particle in a liquid shows a deviation from the Einstein-Smoluchowsky theory that diverges with time. These results are consistent with a generalized theory that takes into account not only the particle inertia but also the inertia of the fluid surrounding the particle. This can lead to a bias in the estimation of the diffusion coefficient from finite-time measurements. We show that the decay of the relative error is polynomial and not exponential and, therefore, can have significant effects at time scales relevant for experiments.

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Giuseppe Pesce, Giorgio Volpe, Giovanni Volpe, Antonio Sasso. 2014-02-27. Longterm Influence of Inertia on the Diffusion of a Brownian Particle. https://doi.org/10.1103/physreve.90.042309

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