Absorption Spectrum

Spectrum consisting of dark absorptionTransfer of energy to a medium as a particle or electromagnetic radiation passes through it. Absorption of electromagnetic radiation is the combined result of Compton scattering, σ, and photoelectric absorption, τ. It may be quantified: where, t = thickness, ρ = density, and μ = mass absorption coefficient, which combines Compton and photoelectric effects (μ = σ + τ). Click on Term to Read More lines superimposed over a continuum spectrum, created when a cooler gas absorbs photons from a hotter continuum source. The image shows the intricate dark Fraunhofer absorption lines superposed on the Sun’s background continuous spectrum.

Dark Fraunhofer absorption lines superposed on the Sun’s background continuous spectrum. Image source: http://s94958815.onlinehome.us/angryastronomer/sunspectrumnoao.jpg