The characteristics of the type of coating depends on their absorptivity, emissivity, transparency, and reflectivity. In this case, Kirchhoff's law of equality of radiative absorptivity and emissivity holds. At any given wavelength the absorptivity of the atmosphere will be equal to the emissivity. With spectrophotometric data the molar absorptivity (or emissivity) values should all be positive. Quantum dots have very sharp wavelengths, high molar absorptivity and quantum yield. The ability of objects to emit is called "emissivity", to absorb radiation is called "absorptivity". The absorption cross-section is closely related to molar absorptivity and mass absorption coefficient. The use of the term "molar absorptivity" for molar attenuation coefficient is discouraged. See also section of "absorptivity" in "emissivity" for information of radiometrical aspect. A closely related concept is molar absorptivity. Moreover, the water vapour continuum absorptivity, molecule for molecule, decreases with pressure decrease. As a result, the molar absorptivity in the near-IR region is typically quite small. The absorber plates in modern panels can have absorptivity of more than 93%. The keyhole leads to a sudden increase in absorptivity quickly deepening the hole. Absorptivity, reflectivity, and emissivity of all bodies are dependent on the wavelength of the radiation.