Pierre-Olivier Chapuis

Effects of spatial dispersion in near-field radiative heat transfer between two parallel metallic surfaces

We study the heat transfer between two parallel metallic semi-infinite media with a gap in the nanometer-scale range. We show that the near-field radiative heat flux saturates at distances smaller than the metal skin depth when using a local dielectric constant and investigate the origin of this effect. The effect of non-local corrections is analysed using the Lindhard-Mermin and BoltzmannMermin models. We find that local and non-local models yield the same heat fluxes for gaps larger than 2nm. Finally, we explain the saturation observed in a recent experiment as a manifestation of the skin depth and show that heat is mainly dissipated by eddy currents in metallic bodies.

Nanoscale heat transfer at contact between a hot tip and a substrate

Hot tips are used either for characterizing nanostructures by using scanning thermal microscopes or for local heating to assist data writing. The tip-sample thermal interaction involves conduction at solid-solid contact as well as conduction through the ambient gas and through the water meniscus. We analyze those three heat transfer modes with experimental data and modeling. We conclude that the three modes contribute in a similar manner to the thermal contact conductance but they have distinct contact radii ranging from 30 nm to 1 μm. We also show that any scanning thermal microscope has a 1-3 μm resolution when used in ambient air.

Near-field induction heating of metallic nanoparticles due to infrared magnetic dipole contribution

We revisit the electromagnetic heat transfer between a metallic nanoparticle and a highly conductive metallic semi-infinite substrate, commonly studied using the electric dipole approximation. For infrared and microwave frequencies, we find that the magnetic polarizability of the particle is larger than the electric one. We also find that the local density of states in the near field is dominated by the magnetic contribution. As a consequence, the power absorbed by the particle in the near field is due to dissipation by fluctuating eddy currents. These results show that a number of near-field effects involving metallic particles should be affected by the fluctuating magnetic fields.

Heat transfer between a nano-tip and a surface

We study quasi-ballistic heat transfer through air between a hot nanometre-scale tip and a sample. The hot tip/surface configuration is widely used to perform non-intrusive confined heating. Using a Monte Carlo simulation, we find that the thermal conductance reaches 0.8 MW m−2 K−1 on the surface under the tip and show the shape of the heat flux density distribution (nanometre-scale thermal spot). These results show that a surface can be efficiently heated locally without contact. The temporal resolution of the heat transfer is a few tens of picoseconds.

Microfluidic Cell Heating Characterized by 3-ω Measurements

Ion beam etching (IBE) was used to microfabricate resistive heaters in indium-tin-oxide (ITO). The device was then closed with a microfluidic chamber and its thermal behavior was investigated using the 3ω method. Experiments and finite element model (FEM) simulations both satisfactorily agreed with a simple one-dimensional model for heat diffusion.Copyright

Thermal Radiation Involving Metallic Nanoparticles in the Near Field

We firstly compare the electric and magnetic polarizabilities of a spherical nanoparticle. We then calculate the electromagnetic heat transfer between a metallic particle and a semi-infinite substrate. We show that the power absorbed by the particle in the near field is due to the magnetic interaction. We then calculate the energy transfer between two metallic nanoparticles and compare the heat dissipated by Joule effect and eddy currents. We find that the heat dissipated due to the magnetic fields is the leading contribution to the heat power. Both calculations show that a number of near-field effects involving metallic particles are affected by the fluctuating magnetic thermal fields.Copyright