Thermal ionization of strontium

Abstract

The theory of thermal ionization of gases was first given by M. N. Saha in a series of papers (1920a, 1920b, 1921) and widely applied by him and others to furnish a satisfactory physical theory of stellar spectra. The theory was further developed by Fowler (1923) to include the different excited states of the atom and of the ionized atom, all of which are simultaneously in thermodynamical equilibrium. At the time when the theory was first formulated the ionization potentials and the spectral characteristics of only a few elements were known, but now we possess almost a complete knowledge of the ionization potentials and the spectra of almost all the elements in their different stages of ionization. Hence a detailed comparison of the theory with experimental results can now be satisfactorily undertaken.