Surfaces for radiative cooling: Silicon monoxide films on aluminum

Efficient radiative cooling is feasible with surfaces which radiate predominantly in the 8–13-μm wavelength range, where the atmosphere emittance is low. The desired reflectance profile was approximated with 1.0 μm of SiO evaporated onto Al. It results from strong lattice absorption in SiO in conjunction with destructive interference. Refrigeration to 40 K below the ambient appears to be possible under suitable climatic conditions.