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Smaller Particles Not Always Faster

Large particles sometimes diffuse faster than assumed

Jülich, 27 April 2017 – The smaller the object, the faster it disperses in its environment: take for example fine grains of sand and rough gravel in the river, or small crumbs and a loaf of bread on the kitchen table. The same behaviour can be seen with microscopically small particles which – excited by surrounding molecules – are distributed through space in the course of time. In 1905, Albert Einstein was able to provide evidence demonstrating that the speed of this Brownian motion is inversely proportional to the radius of a particle, that is to say its size. Scientists from Forschungszentrum Jülich, KU Leuven, and the CRPP research centre in Bordeaux have now discovered an exception to this rule. For their experiments, they used a lamellar system in which the large particles are more mobile than the small ones.

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