Experimental Evidence for Algebraic Double-Layer Forces

TL;DR

This paper provides experimental evidence that electric double-layer forces can decay algebraically with distance, challenging the conventional exponential decay model, and identifies different algebraic regimes in various ionic conditions.

Contribution

It demonstrates experimentally that double-layer forces can decay algebraically, revealing new regimes beyond the traditional exponential decay model.

Findings

Double-layer forces decay as inverse square of distance in certain regimes.

Algebraic decay observed in both strongly overlapping and counterion-only regimes.

Different algebraic regimes identified at small separation distances.

Abstract

According to conventional wisdom electric double-layer forces normally decay exponentially with separation distance. Here we present experimental evidence of algebraically decaying double-layer interactions. We show that algebraic interactions arise in both strongly overlapping as well as counterion-only regimes, albeit the evidence is less clear for the former regime. In both of these cases the disjoining pressure profile assumes an inverse square distance dependence. At small separation distances another algebraic regime is recovered. In this regime the pressure decays as the inverse of separation distance.