Notes. E_low is the excitation energy of the lower level, log gf the oscillator strength. The last column gives the reference for the gf-value. The oscillator strength f is a measure of the strength of an atomic transition between two excited levels caused by interaction with photons. The line absorption coefficient is directly proportional to f, and g is the statistical weight of the lower level determined by its rotational quantum number. For further details see e.g. Wahlgren (2010) or Gray (2005).

Reference. 1) Kurucz (2010); 2) May et al. (1974); 3) Drozdowski et al. (1997).