Stokes formula and density perturbances for driven tracer diffusion in an adsorbed monolayer

TL;DR

This paper investigates the frictional resistance experienced by a biased tracer molecule moving through a monolayer adsorbed on a surface, deriving a Stokes-like formula and analyzing particle distribution.

Contribution

It introduces a novel Stokes formula analog for 2D adsorbed monolayers and calculates the associated friction coefficient and particle distribution under bias.

Findings

Force on tracer exhibits viscous-like behavior at small driving forces.

Derived a Stokes formula analog for 2D adsorbed monolayers.

Calculated stationary particle distribution around the driven impurity.

Abstract

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 viscous-like 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.