WRH professor Saulius Juodkazis (School of Materials and Chemical Technology) published a paper in Appl. Sci.

“Femtosecond Laser Textured Surfaces for Radiative Cooling: Black Metals”

https://doi.org/10.3390/app15042076

Abstract:
IThere is a growing need for novel methods to modify the surfaces of a wide range of materials over large areas. Here, we demonstrate the creation of low-reflectance (𝑅<2%R<2%) surfaces in the near-to-mid infrared (IR) spectral window of 2–20 μμm by ablating W, Al, and Cu with high average intensity 20–120 TW/cm², 200 fs laser pulses at 1030 nm wavelength. The chemical modifications of the surfaces by laser ablation under ambient room conditions were analyzed using X-ray photoelectron spectroscopy (XPS). The results show a consistent decrease in the metallic component, accompanied by an increase in metal oxides. Energy dispersive spectroscopy (EDS) showed a similar increase in oxygen content over a micrometer depth scale. The reduced refractive index of the metal oxides compared to the corresponding metals contributes to the reduction in IR reflectance, combined with the formation of 3D hierarchically textured surface structures. These IR-black metals exhibit great potential for radiative cooling at elevated temperatures relevant to industrial and space applications.