Electron Paramagnetic Resonance Spectra of ${\mathrm{Cr}}^{+}$, ${\mathrm{Mn}}^{++}$, and ${\mathrm{Fe}}^{3+}$ in Cubic ZnS

The paramagnetic spectra of the three ${}_{}{}^6{}_{}{}^{}S_{\frac{5}{2}}^{}{}_{}{}^{}$ ions ${\mathrm{Cr}}^{+}$, ${\mathrm{Mn}}^{++}$, and ${\mathrm{Fe}}^{3+}$ have been measured in cubic ZnS. The paramagnetic resonance parameters $g$, $a$, and $A$ are compared to the theories for these parameters for the ${}_{}{}^6{}_{}{}^{}S_{\frac{5}{2}}^{}{}_{}{}^{}$ state. It is found that the covalent character of the lattice must be taken into account. For the parameter $A$, a linear relation is found to exist for all three ions between the value of $A$ and the ionicity of the lattice. The extrapolated value of $A$ at 100% ionicity is found to be in agreement with the calculations of Watson and Freeman. The values of $g$ and $a$ are found to be in qualitative agreement with the theories of Watanabe and Gabriel, Johnston and Powell. Exact calculations of the parameters $g$ and $a$ require a detailed knowledge of the environment of the ion.