Shape-dependence of near-field heat transfer between a spheroidal nanoparticle and a flat surface

Abstract

We study the radiative heat transfer between a spheroidal metallic nanoparticle and a planar metallic sample for near-and far-field distances. In particular, we investigate the shape dependence of the heat transfer in the near-field regime. In comparison with spherical particles, the heat transfer typically varies by factors between 1/2 and 2 when the particle is deformed such that its volume is kept constant. These estimates help to quantify the deviation of the actual heat transfer recorded by a near-field scanning thermal microscope from the value provided by a dipole model which assumes a perfectly spherical sensor.

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].…”

Spheroidal nanoparticles as thermal near-field sensors

“…As expected, one observes r E α ≫ 1 for prolate, rice grain-like particles (R b /R a ≪ 1), whereas r H α ≫ 1 for strongly oblate, pancake-like particles (R b /R a ≫ 1), in which the magnetic fields can easily induce eddy currents. We expect that the model yields reliable results at least in the interval 1/5 ≤ R b /R a ≤ 5 of the aspect ratio [27].…”

Fundamentals and Applications of Near-Field Radiative Energy Transfer

“…This result was experimentally validated as will be discussed in the following section. A further research was conducted to seek the shape dependence of near-field radiative heat transfer when a spheroidal metallic nanoparticle is in proximity to a planar metallic sample (Huth et al, 2010). By changing the aspect ratio of a spheroidal particle from 1/5 (long axis perpendicular to the surface) to 5 (long axis parallel to the surface) while fixing its volume, they predicted that the total radiative heat transfer between a gold spheroid at 100 K and a gold planar surface Fig.…”