Eur. Phys. J. B 24, 541-547 (2001)
https://doi.org/10.1007/s10051-001-8707-0

Test of the universality of the critical adsorption profile by neutron reflection

¹ Service de Physique de l'État Condensé, C.E.N. Saclay, 91191 Gif-sur-Yvette, France
² Laboratoire Léon Brillouin, C.E.N. Saclay, 91191 Gif-sur-Yvette, France
³ UMR 6521, U.B.O., 6 avenue Victor Le Gorgeu, 29285 Brest, France

Corresponding author: ^a zalczer@spec.saclay.cea.fr

Received: 30 May 2001
Published online: 15 December 2001

Abstract

Using neutron reflectivity, we directly and self-consistently obtained all the parameters of the critical adsorption profile of three critical mixtures (n-hexane+perfluorohexane, deuterated methanol+cyclohexane and methanol+deuterated cyclohexane) assuming only a Liu-Fisher form for the profile. The characteristic exponent and the amplitude ratio which can be deduced from the neutron spectra alone are in good agreement with one another, with ellipsometric data and with theoretical values. Owing to auxiliary measurements of coexistence curves and correlation lengths, we could also check the amplitude of the intermediate and distal parts of the profile with good agreements for the methanol cyclohexane mixtures only. The adsorbed amount is much greater in the n-hexane+perfluorohexane mixture where both the power-law amplitude and the characteristic length of the profile are affected.