1. Choice of mean ionization potentials:
1 … Mean Ionization of Berger-Seltzer
2 … Mean Ionization of Duncumb-Da Casa
3 … Mean Ionization of Ruste and Zeller
4 … Mean Ionization of Springer
5 … Mean Ionization of Wilson
6 … Mean Ionization of Heinrich
7 … Mean Ionization of Bloch (Love-Scott)
8 … Mean Ionization of Armstrong (Springer-Berger)
9 … Mean Ionization of Joy (Wilson-Berger)
Calculation #2 should only be used if the Philibert (#1) absorption correction and Duncumb-Reed atomic number (#1) correction are employed. Selection #1 is the default.