Stokes formula and density perturbances for driven tracer diffusion in an adsorbed monolayer
We study the intrinsic friction of monolayers adsorbed on solid surfaces from a gas phase or vapor. Within the framework of the Langmuir model of delocalized adsorption, we calculate the resistance offered by the mobile adsorbate's particles to some impure tracer molecule, whose diffusive random motion is biased by a constant external force. We find that for sufficiently small driving forces the force exerted on the tracer shows viscouslike behavior. We derive then the analog of the Stokes formula for two-dimensional adsorbates, calculate the corresponding friction coefficient, and determine the stationary particle distribution in the monolayer as seen from the driven impurity.
Benichou
O
Laboratoire de Physique Theorique des Liquides (CNRS-UMR 7600), Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, France.
Cazabat
AM
De Coninck J
Moreau
M
Oshanin
G