Active anisotropic diffusion of microparticles in nematic lyotropic chromonic liquid crystal powered by light

TL;DR

This study demonstrates how light can induce active, anisotropic diffusion of microparticles in nematic lyotropic chromonic liquid crystals by disrupting molecular stacking, revealing a novel non-equilibrium transport mechanism.

Contribution

It introduces a new light-driven active diffusion mechanism in LCLCs, showing how illumination causes anisotropic active transport of microparticles.

Findings

Light induces active anisotropic diffusion of microparticles.

Disruption of molecular stacking causes non-equilibrium transport.

Diffusion is anisotropic and driven by light absorption.

Abstract

We explore the diffusion dynamics of a Brownian microparticle in a lyotropic chromonic liquid crystal (LCLC). In the planarly oriented nematic phase, the microparticle exhibits levitation and anisotropic two-dimensional diffusion. Upon illumination with light resonant with the absorption spectrum of the solution, we observe a transition to active anisotropic diffusion, driven by the disruption of the molecular stacking in the liquid crystal. Notably, while light absorption increases both the molecular kinetic energy and the overall temperature of the solution, it manifests at the microscopic level as anisotropic active diffusion of the microparticles, revealing a novel light-driven non-equilibrium transport mechanism.