Measurement of Anomalous Heat Transfer on the Nanometer Scale

We have used a bimaterial AFM cantilever technique to measure radiative heat transfer on a nanometer length scale. According to theory, radiative heat transfer between two objects will increase drastically at distances less than the thermal wavelength λ = (cħ)/( kBT) divided by 2π. This increase can be accounted for by considering the contribution of evanescent waves produced by surface phonon polaritons. While this effect has been recognized for some time it has only been measured quantitatively very recently. Our goal was to duplicate these measurements which required the construction of a specialized experimental apparatus.;A special purpose microcalorimeter which utilized a bimaterial AFM cantilever in the pendulum geometry was constructed. Heat flux into the cantilever caused it to bend at a measured rate of 0.34 nW/nm. The deformation of this cantilever was measured using an optical fiber interferometer which was capable of measuring displacements of < 1Å.