The mass absorption coefficient, mass scattering coefficient and mass extinction coefficient each with units m 2 kg -1 are defined respectively as α/ρ, σ/ρ and ε/ρ, where ρ is the density (kg m -3 ) o...The mass absorption coefficient, mass scattering coefficient and mass extinction coefficient each with units m 2 kg -1 are defined respectively as α/ρ, σ/ρ and ε/ρ, where ρ is the density (kg m -3 ) of the medium. The atomic (or molecular) absorption, scattering and extinction coefficients are respectively α/N, σ/N and ε/N, where N is the number density (atoms or molecules per unit volume), with units of m 2 /atom (or molecule).
