Femtosecond laser blackening of platinum

Using a femtosecond laser processing technique, we produce the black platinum with absorptance of about 95% over a broad wavelength range from ultraviolet to infrared. From scanning electron microscopy and energy dispersive x-ray spectroscopy studies, we find that the enhanced absorption of the black metal is due to a variety of nano- and microscale surface structures. Using a unique calorimetry technique, we perform a shot-to-shot comparison study of the metal absorption change in air and vacuum. Our study shows that the blackening process for platinum is more efficient in vacuum.