Adsorption anomalies in a 2D model of cluster-forming systems

TL;DR

This study uses Monte Carlo simulations to explore how particles with competing interactions adsorb onto a boundary, revealing unusual behaviors like adsorption maxima and oscillatory density profiles near phase transitions in cluster-forming systems.

Contribution

It demonstrates non-standard adsorption phenomena in a 2D SALR model, highlighting differences from simple fluids during structural transitions.

Findings

Adsorption exhibits a maximum during the transition from disordered to cluster fluid.

Adsorption decreases with increasing chemical potential when clusters dominate.

Density and correlation functions show oscillatory decay near the wall.

Abstract

Adsorption on a boundary line confining a monolayer of particles self-assembling into clusters is studied by MC simulations. We focus on a system of particles interacting via competing interaction potential in which effectively short-range attraction is followed by long-range repulsion, mimicking the so called SALR system. For the chemical potential values below the order-disorder phase transition the adsorption isotherms were shown to undergo non-standard behavior, i. e. the adsorption exhibits a maximum upon structural transition between structureless and disordered cluster fluid. In particular, we have found that the adsorption decreases for increasing chemical potential when (i) clusters dominate over monomers in the bulk, (ii) the density profile in the direction perpendicular to the confining line exhibits an oscillatory decay, (iii) the correlation function in the layer near the adsorption wall exhibits an oscillatory decay in the direction parallel to this wall. Our report indicates striking differences between simple and complex fluid adsorption processes.