Attenuation Coefficients for Molecules (and mixtures)
Calculate mole fraction fmi for each atom type i in a molecule or mixture, subject to Sifmi = 1
Recognize that, in a molecule, fmi is proportional to the product of the number of atoms of that type in the molecule, ni, and to the atomic weight of that atom, mi:fmi = Qni mi (Q a constant to be determined)
Thus Sifmi = Si Qni mi = 1 so Q = (Si ni mi)-1
Then (s/r) for the compound will be(s/r)Tot = Sifmi(s/r)i