Splitting of theS526state of substitutionalMn2+inSrCl2by an applied electric field

The effect of an applied electric field on the EPR signal of ${\mathrm{SrCl}}_2$:${\mathrm{Mn}}^{2+}$ was measured at 77°K. The paramagnetic parameters obtained experimentally without an electric field are $b_4=+1.05\mathrm{}\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, $A=82.5\mathrm{}\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, and $g=2.0057\mathrm{}$. The crystal-field parameter to be introduced in order to explain the observed additional splitting is $b_2^0=11.2\mathrm{}\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$ for $E=2.4\mathrm{}\times {10}^7$ V/m. The electric field effect which shows axial symmetry about the crystallographic axes, can be explained by a displacement of the ${\mathrm{Mn}}^{2+}$ ion along directions. From a point-ion lattice calculation taking into account the effect of induced dipoles we can estimate the magnitude of this displacement to be $\Delta =0.11\mathrm{}-0.16$ Å for $E=2.4\mathrm{}\times {10}^7$ V/m.