Producing selective absorption at a coated metal surface

Unoxidized metal surfaces have inadequate absorption coefficients in the incident wavelength range of 0.2-2.5 micrometers, this range being converted to heat. One way of selectively increasing the absorption coefficient of a photothermal energy converter in this wavelength range is to deposit a layer of material that absorbs much of the incident flux but as far as possible does not increase the emissivity in the range 4-40 micrometers, which corresponds to a working temperature range of about 200-300 degrees C. This method is examined in this article.