A thermokinetic approach to radiative heat transfer at the nanoscale

TL;DR

This paper introduces a thermokinetic model for nanoscale radiative heat transfer that incorporates phonon-photon coupling and non-Debye relaxation, accurately fitting experimental data and explaining energy transfer across various configurations.

Contribution

It presents a novel thermokinetic framework including a lognormal distribution for relaxation modes, advancing understanding of nanoscale radiative heat transfer beyond existing models.

Findings

The model accurately fits experimental thermal conductance data.

Non-Debye relaxation behavior explains phonon-photon coupling.

The approach applies across different geometries and distances.

Abstract

Radiative heat exchange at the nanoscale presents a challenge for several areas due to its scope and nature. Here, we provide a thermokinetic description of microscale radiative energy transfer including phonon-photon coupling manifested through a non-Debye relaxation behavior. We show that a lognormal-like distribution of modes of relaxation accounts for this non-Debye relaxation behavior leading to the thermal conductance. We also discuss the validity of the fluctuation-dissipation theorem. The general expression for the thermal conductance we obtain fits existing experimental results with remarkable accuracy. Accordingly, our approach offers an overall explanation of radiative energy transfer through micrometric gaps regardless of geometrical configurations and distances.