On the thermal vacuum radiation of nanoparticles and their ensembles

Thermal radiation of spherical particles and their ensembles is analyzed within the framework of fluctuation electrodynamics. Numerical calculations are carried out for spherical gold and graphite particles with allowance for real material properties and polarizabilities. It is shown that the maximum radiated power of single graphite particles in vacuum reaches 95% of the radiation power of a black body with a temperature of 3000 K and a radius of 200 nm. Moreover, the presence of neighboring particles reduces the emissivity of a single particle by 3–40%. For gold particles, radiation power does not exceed 8% of the black-body radiation and has an oscillating dependence on the distance with a maximum amplitude of 0.8% of the constant component.