Spectral mapping of heat transfer mechanisms at liquid-solid interfaces

TL;DR

This study uses molecular dynamics to analyze the spectral distribution of heat transfer at liquid-solid interfaces, revealing the key vibrational modes involved in energy transfer and how adhesion influences heat flow efficiency.

Contribution

It provides a detailed spectral analysis of liquid-solid heat transfer mechanisms, highlighting the roles of surface modes and the impact of adhesion on energy transfer efficiency.

Findings

Surface modes at the Brillouin zone edge are crucial for energy transfer.

Strong adhesion enhances coupling of in-plane modes, increasing heat transfer.

Energy transfer can occur up to the solid's cut-off frequency.

Abstract

Thermal transport through liquid-solid interfaces plays an important role in many chemical and biological processes, and better understanding of liquid-solid energy transfer is expected to enable improving the efficiency of thermally driven applications. We determine the spectral distribution of thermal current at liquid-solid interfaces from nonequilibrium molecular dynamics, delivering a detailed picture of the contributions of different vibrational modes to liquid-solid energy transfer. Our results show that surface modes located at the Brillouin zone edge and polarized along the liquid-solid surface normal play a crucial role in liquid-solid energy transfer. Strong liquid-solid adhesion allows also for the coupling of in-plane polarized modes in the solid with the liquid, enhancing the heat transfer rate and enabling efficient energy transfer up to the cut-off frequency of the solid. Our results provide fundamental understanding of the energy transfer mechanisms in liquid-solid systems and enable detailed investigations of energy transfer between, e.g., water and organic molecules.