Light-induced directed self-propulsion of active nanosized particles in a three-dimensional Brownian environment probed by heterodyne photon correlation laser spectroscopy.

Christoulaki, Anastasia; Buhler, Eric · Phys Rev E · 2025

basic_science · Level V

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Abstract

The motion of photocatalytic silver chloride nanoparticles (AgCl NPs) with radius R∼70nm that use electrolyte self-diffusiophoresis to achieve autonomous propulsion is fully characterized using heterodyne dynamic light scattering, allowing accurate determination of both ballistic and random Brownian diffusion contributions. This technical approach made it possible to reveal the directional self-propulsion of a very large ensemble of light-activated small-size nanoparticles in a 3D spatially nonconfined Brownian environment. Their speeds and direction are easily controlled using an ultraviolet (UV) irradiation external stimulus. We also report the programmable self-assembly and collective behavior of photoactive AgCl NPs.