DEPLETION FORCES BETWEEN 2 SPHERES IN A ROD SOLUTION

We study the depletion interaction between spherical particles of radi us R immersed in a dilute solution of rigid rods of length L. The comp uted interaction potential is, within numerical accuracy, exact for an y value of L/R. In particular we find that for L similar to R, the dep th of the depletion well is smaller than the prediction of the Derjagu in approximation. Our results bring new light into the discussion on t he lack of phase separation in colloidal mixtures of spheres and rods.