Near-field radiative heat transfer between a sphere and a substrate

TL;DR

This paper demonstrates a sensitive measurement technique for near-field radiative heat transfer between a microsphere and a substrate, revealing significant near-field enhancement beyond classical blackbody predictions.

Contribution

It introduces a novel AFM-based method to measure near-field radiative transfer, providing experimental evidence of heat transfer enhancement at nanometer-scale gaps.

Findings

Strong near-field effects observed in heat transfer

Heat transfer exceeds Planck blackbody radiation predictions

Method enables precise measurement of near-field radiative phenomena

Abstract

Near-field force and energy exchange between two objects due to quantum electrodynamic fluctuations give rise to interesting phenomena such as Casimir and van der Waals forces, and thermal radiative transfer exceeding Planck's theory of blackbody radiation. Although significant progress has been made in the past on the precise measurement of Casimir force related to zero-point energy, experimental demonstration of near-field enhancement of radiative heat transfer is difficult. In this work, we present a sensitive technique of measuring near-field radiative transfer between a microsphere and a substrate using a bi-material atomic force microscope (AFM) cantilever, resulting in "heat transfer-distance" curves. Measurements of radiative transfer between a sphere and a flat substrate show the presence of strong near-field effects resulting in enhancement of heat transfer over the predictions of the Planck blackbody radiation theory.