Variation of muonic x-ray spectra with electronic structure: A study of iron compounds

The K series of muonic x rays of iron has been measured from ${\mathrm{FeCl}}_3$, ${\mathrm{Fe}}_2$ ${\mathrm{O}}_3$, ${\mathrm{K}}_3$Fe(CN${)}_6$, and aqueous solutions of Fe(${\mathrm{NO}}_3$ ${)}_3$ and ${\mathrm{K}}_3$Fe(CN${)}_6$. Significant differences in the x-ray-intensity pattern were observed and related to the structure of the outer electrons of Fe in these compounds. The influence of the ionic radius and ionic charge and of hydrogen in aqueous solutions is discussed. The importance of open d- or f-electron configurations is demonstrated.