Send to

Choose Destination
See comment in PubMed Commons below
Phys Rev Lett. 2005 Oct 14;95(16):160601. Epub 2005 Oct 11.

Direct observation of nondiffusive motion of a Brownian particle.

Author information

  • 1Institut de Physique de la Matière Complexe, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland.


The thermal position fluctuations of a single micron-sized sphere immersed in a fluid were recorded by optical trapping interferometry with nanometer spatial and microsecond temporal resolution. We find, in accord with the theory of Brownian motion including hydrodynamic memory effects, that the transition from ballistic to diffusive motion is delayed to significantly longer times than predicted by the standard Langevin equation. This delay is a consequence of the inertia of the fluid. On the shortest time scales investigated, the sphere's inertia has a small, but measurable, effect.

PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for American Physical Society
    Loading ...
    Support Center