Volume 249, 2024

Collective modes and quantum effects in two-dimensional nanofluidic channels

Abstract

Nanoscale fluid transport is typically pictured in terms of atomic-scale dynamics, as is natural in the real-space framework of molecular simulations. An alternative Fourier-space picture, that involves the collective charge fluctuation modes of both the liquid and the confining wall, has recently been successful at predicting new nanofluidic phenomena such as quantum friction and near-field heat transfer, that rely on the coupling of those fluctuations. Here, we study the charge fluctuation modes of a two-dimensional (planar) nanofluidic channel. Introducing confined response functions that generalize the notion of surface response function, we show that the channel walls exhibit coupled plasmon modes as soon as the confinement is comparable to the plasmon wavelength. Conversely, the water fluctuations remain remarkably bulk-like, with significant confinement effects arising only when the wall spacing is reduced to 7 Å. We apply the confined response formalism to predict the dependence of the solid–water quantum friction and thermal boundary conductance on channel width for model channel wall materials. Our results provide a general framework for Coulomb interactions of fluctuating matter under nanoscale confinement.

Graphical abstract: Collective modes and quantum effects in two-dimensional nanofluidic channels

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Article information

Article type
Paper
Submitted
01 jún. 2023
Accepted
22 jún. 2023
First published
28 jún. 2023
This article is Open Access
Creative Commons BY license

Faraday Discuss., 2024,249, 162-180

Collective modes and quantum effects in two-dimensional nanofluidic channels

B. Coquinot, M. Becker, R. R. Netz, L. Bocquet and N. Kavokine, Faraday Discuss., 2024, 249, 162 DOI: 10.1039/D3FD00115F

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