What controls the thickness of wetting layers near bulk criticality?
We study the thickness of wetting layers in the binary-liquid mixture cyclohexane methanol. Far from the bulk critical point, the wetting layer thickness is independent of temperature, resulting from the competition between van der Waals and gravitational forces. Upon approaching the bulk critical temperature [t=(T(c)-T)/T(c)-->0], we observe that the wetting layer thickness diverges as t(-beta) with effective critical exponent beta=0.23+/-0.06. This is characteristic of a broad, intermediate scaling regime for the crossover from van der Waals wetting to critical scaling. We predict beta=beta/3 approximately 0.11, with beta the usual bulk-order parameter critical exponent, showing a small but significant difference with experiment.
Fenistein
Denis
D
Laboratoire de Physique Statistique, Ecole Normale Supérieure, 24, Rue Lhomond, F-75231 Paris Cedex 05, France.
Bonn
Daniel
D
Rafaï
Salima
S
Wegdam
Gerard H
GH
Meunier
Jacques
J
Parry
Andrew O
AO
da Gama
Margarida M Telo
MM