Exciton-mediated optical control of liquid-solid friction
Timur Pryadilin, Alexey Kavokin, Baptiste Coquinot
TLDR
This paper presents a microscopic theory showing how excitons can optically control liquid-solid friction in nanofluidic systems, reducing slip.
Key contributions
- Develops a microscopic theory for exciton-mediated solid-liquid friction.
- Derives analytical formulas for tunable excitonic friction, reducing slip length.
- Reproduces experimental measurements of nanotube diffusion reduction without fitting.
- Establishes excitons as a mechanism for optical control of nanofluidic transport.
Why it matters
This research introduces a novel mechanism for optically controlling fluid flow at the nanoscale, providing a theoretical framework validated by experiments. It opens new avenues for designing advanced nanofluidic devices and developing optical probes for flow velocity in nanochannels.
Original Abstract
Interfacial friction in nanofluidic systems can arise from fluctuation-induced coupling between liquid charge fluctuations and the internal excitations of the confining solid. Here, we develop a microscopic theory of exciton-mediated solid-liquid friction based on the coupling between optically generated excitons and charge fluctuations in water. We distinguish between static excitons, localized by disorder or functionalization, and dynamic excitons, which interact with water through polarization fluctuations. In both cases, we derive analytical formulas for the excitonic friction, which is experimentally tunable and can significantly reduce the slip length and thereby the hydraulic permeability of nanochannels. Applying our framework to carbon nanotubes, we quantitatively reproduce the recent measurements of Kistwal et al., showing a reduction of nanotube diffusion under optical excitation, without fitting parameters. More broadly, our results establish excitons as a mechanism to optically control nanofluidic transport and suggest that excitonic photoluminescence could provide an optical probe of flow velocity inside nanochannels.
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