Colloidal particles adsorption fluctuations: experimental and kirk- wood buff integrals approaches
Résumé
Colloidal particles (amidine latex, 1 μm in diameter) in aqueous solution are put in contact with a
glass slide under ambient conditions where they adsorb. The particle concentration is fixed during
the experiment by mean of an infinite reservoir. Using a simple optical microscope, 240 x 320 μm2
images of the population of the adsorbed particles are taken while the glass slide and the solution are
at equilibrium. Analyzing the surface population we get the direct access to the isotherm, i.e. sur-
face concentration as a function of solution concentration. The isotherm is alternatively obtained
both from the density fluctuation and/or from the pair distribution function and the use of the Kirk-
wood Buff Integral. The results clearly show the equality of the chemical potential between the two
phases.