X-Ray Emission Spectra and Electronic Energy Bands of Compounds

Measurements of emission wave-lengths in the $K\beta$ group of Ca and S in CaS and CaS${\mathrm{O}}_4$, of Mg and S in MgS, of S in SrS and BaS, of Ca and Cl in Ca${\mathrm{Cl}}_2$ have been made from the secondary radiation from pressed blocks of the salts. An attempt is made to determine the origin of as many x-ray lines as possible by means of electronic energy band systems in the cases of CaS, MgS, and ZnS. The $K{\beta }_5$ line of Zn in ZnS and the $K{\beta }_1$ line of Mg in MgS are found to be due to cross transitions from the outermost filled band of the negative ion.