FYI: The reason I include this article is that surface topology can tune and enhance absorption by many orders of magnitude.
"Thermal energy harvesting antennas by more than 10,000 to 100,000 times with tiny holes in copper" http://nextbigfuture.com/2015/10/thermal-energy-harvesting-antennas-by.html "Park's team uses software to analyze how the nanoscale topology of a surface -- its bumps, holes or grooves -- changes the way that electromagnetic radiation interacts with the surface. In some instances the geometry supports the formation of a wave of rippling electronic charges, called a plasmon, that hugs the surface." "We design the surface to support a surface wave, because the presence of the wave offers a new avenue for engineering thermal emission," Park said. For the case of optimizing thermal energy harvesting, the researchers found they could "spectrally tune" a surface to emit more radiation at 1 THz frequency. "Turning Up the Heat: Holey Metamaterials Enhance Thermal Energy Harvesting" http://www.newswise.com/articles/turning-up-the-heat-holey-metamaterials-enh ance-thermal-energy-harvesting -Mark Iverson
