In many cases, by forming nanostructures on the surface, direct laser processing of material surfaces is a powerful method for changing those materials’ optical (light absorption) and electrical properties. The aspect of random chance that affects the size and geometry of the small-scale structures themselves has made it difficult to regulate precisely those surface modifications and, consequently, the modified properties of the material. Femtosecond lasers have made it possible to operate more precisely and build structures with sub-wavelength regularity. But it hasn’t remained easy to design the resulting surface properties exactly.
Recently, a study showed how to alter the morphology of surface nanostructures and, in turn, the treated metal’s spectral light absorption. The discovery may immediately benefit thermal-solar technology by increasing the performance of thermoelectric generation in tungsten-based absorbers compared to untreated tungsten surfaces.
The experts claimed that this surface, in addition to improving solar energy absorption, also lowers heat dissipation at other wavelengths, effectively creating the first perfect metallic solar absorber. Through a complicated process involving resonance modes generated between the individual structures and the behavior of surface plasmons, delocalized electron oscillations that can exist on a material’s surface under the right circumstances, nanostructures can modify the spectral absorption range of a metallic surface.
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