Isotope effect on radiative thermal transport

TL;DR

This paper predicts that isotopic composition can drastically alter radiative heat transfer in polar dielectrics at room temperature, revealing a significant isotope mass effect on phonon-mediated resonant absorption.

Contribution

It demonstrates the potential to engineer radiative thermal transport through isotopic variation, a novel insight into thermal management at the nanoscale.

Findings

Radiative heat flow varies over 3 orders of magnitude with isotopic composition.

Isotope effects significantly influence phonon resonances in polar dielectrics.

Metallic and doped semiconductor materials show negligible isotope effects.

Abstract

Isotope effects on heat conduction and convection have been known for decades. However, whether thermal radiation can be isotopically engineered remains an open question. Here, we predict over 3-orders-of-magnitude variation of radiative heat flow with varying isotopic compositions for polar dielectrics at room temperature. We reveal this as an isotope mass effect which induce phonon line shift and broadening that in turn affect phonon-mediated resonant absorption both in the near and far field. In contrast, the isotope effect is negligible for metals and doped semiconductors which largely depend on free carriers. We also discuss the role of temperature with regard to surface mode excitation.