# Onset of anomalous diffusion in colloids confined to quasi-monolayers

## TL;DR

This paper investigates how colloidal particles transition from normal to anomalous diffusion when confined in quasi-monolayers, considering the effects of out-of-plane fluctuations and hydrodynamic interactions.

## Contribution

It provides a theoretical and numerical analysis of the crossover from normal to anomalous diffusion in quasi-monolayers with out-of-plane particle fluctuations.

## Key findings

- Identification of the conditions leading to anomalous diffusion
- Quantitative description of the crossover behavior
- Impact of out-of-plane fluctuations on collective diffusion

## Abstract

It has been recently shown that a colloidal monolayer, e.g., formed at a fluid interface or by means of a suitable confining potential, exhibits anomalous collective diffusion. This is a consequence of the hydrodynamic interactions mediated by the three-dimensional (3D) ambient fluid when the particles are confined to reside on a two-dimensional (2D) manifold. We study theoretically and with numerical simulations the crossover from normal to anomalous diffusion as the particles are, in real systems, confined by a 3D external potential and thus have the possibility to fluctuate out of the 2D manifold, thus forming actually a quasi-monolayer.