Heat transfer between nanoparticles: Thermal conductance for near-field interactions

Abstract

We analyze the heat transfer between two nanoparticles separated by a distance lying in the near-field domain in which energy interchange is due to the Coulomb interactions. The thermal conductance is computed by assuming that the particles have charge distributions characterized by fluctuating multipole moments in equilibrium with heat baths at two different temperatures. This quantity follows from the fluctuation-dissipation theorem for the fluctuations of the multipolar moments. We compare the behavior of the conductance as a function of the distance between the particles with the result obtained by means of molecular dynamics simulations. The formalism proposed enables us to provide a comprehensive explanation of the marked growth of the conductance when decreasing the distance between the nanoparticles.

Mesoscopic Non-Equilibrium Thermodynamics: Application to Radiative Heat Exchange in Nanostructures

“…4, we have represented the heat conductance as a function of the distance d between the NPs of different radii. This figure shows a significant enhancement of the heat conductance when d decreases until 2D , which, as has been shown in a previous work by means of electromagnetic calculations and using the fluctuation-dissipation theorem (Pérez-Madrid et al, 2008), is due to multipolar interactions. In more extreme conditions when the NPs come into contact to each other, a sharp fall occurs which can be interpreted as due to an intricate conglomerate of energy barriers inherent to the amorphous character of these NPs generated by the strong interaction.…”

“…This procedure constitutes the so-called fluctuating electrodynamics (Domingues et al, 2005). Expressions for the fluctuation-dissipation theorem can also be found even when the dipolar approximation is no longer valid since due to the particular charge distribution, higher order multipoles become important (Pérez-Madrid et al, 2008). Such as in the case of two interacting NPs illustrated in Fig.…”

Modulation of near-field heat transfer between two gratings

“…Moreover, very recent experiments [6,7] were in good quantitative agreement with theoretical predictions. On the theoretical side, we can highlight the studies of the heat flux for layered media [8,9], for photonic crystals [10], metamaterials [11], and porous media [12].In addition, the dependence of the heat transfer on the geometry has attracted much interest and has been investigated in a sphere-plane geometry [13,14], for spheroidal particles above a plane surface [15] and between two spheres or nanoparticles [16][17][18][19][20]. Somewhat more applied studies have attempted to take advantage of the potential of the tremendous increase of the radiative heat flux on the nanoscale for thermal imaging of nanostructured surfaces [21][22][23][24].…”

“…In addition, the dependence of the heat transfer on the geometry has attracted much interest and has been investigated in a sphere-plane geometry [13,14], for spheroidal particles above a plane surface [15] and between two spheres or nanoparticles [16][17][18][19][20]. Somewhat more applied studies have attempted to take advantage of the potential of the tremendous increase of the radiative heat flux on the nanoscale for thermal imaging of nanostructured surfaces [21][22][23][24].…”

Non-equilibrium Stefan–Boltzmann law

“…On the other hand, when L λ T (i.e. low frequencies) we deal with the problem of cage-diffusion [16], therefore the diffusion coefficient must depend on the ratio λ T /L or equivalently on the frequency [17,18].…”