SKM 2023 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 11: Poster Session I

BP 11.4: Poster

Dienstag, 28. März 2023, 12:30–15:30, P1

Self-propulsion of Janus particles at small laser powers and the impact of salt — •Franziska Braun and Regine von Klitzing — Institute for Condensed Matter Physics, Technische Universität Darmstadt, D-64289 Darmstadt

The anisotropy in the architecture allows Janus particles to create an out-of-equilibrium state around the particle in the solvent, which is a necessary condition for triggering self-propulsion. One possible propulsion mechanism is thermophoretic self-propulsion. When laser light (λ = 532 nm) illuminates a gold-capped particle, a local temperature gradient is generated along the particle surface due to surface plasmon excitation of the gold cap. This gradient perturbs the equilibrium conditions of the surrounding medium and leads to self-propulsion.

This contribution focuses on an intensive study of the self-propulsion behavior of self-thermophoretic Janus particles. For this purpose, the movement of the Janus particles is tracked in real-time with dark-field microscopy (DFM). First, the thermophoretic velocity of Au-PS particles is investigated focusing on very low laser powers below 10 mW. Surprisingly, the study shows a deviation of the thermophoretic velocity from the expected linear behavior in the low laser power regime. Secondly, the influence of salt ions on the self-propulsion behavior of such Au-PS particles is described.