Photosensitive Electron Spin Resonance ofSn3+in Zinc Sulfide

Electron spin resonance due to ${\mathrm{Sn}}^{3+}$ in hexagonal ZnS crystal has been examined. The signal is much enhanced with uv excitation and quickly decreased by irradiation of light of around 550 mμ. It is found that $g=2.0075\mathrm{}\pm 0.0005$, and that $\mathrm{}\left|A\right|=0.5207\mathrm{}\pm 0.0005$ ${\mathrm{cm}}^{-1\mathrm{}}$ for ${\mathrm{Sn}}^{117}$, and $\mathrm{}\left|A\right|=0.5448\mathrm{}\pm 0.0005$ ${\mathrm{cm}}^{-1\mathrm{}}$ for ${\mathrm{Sn}}^{119}$. The sign and the order of magnitude of the observed $g$ shift are well interpreted by the previously proposed model that the $g$ shift of substitutional trivalent impurity of Group-$\mathrm{IV}B$ elements in ZnS is mainly caused by the processes of charge transfer into the ligand anions through the spin-orbit interaction. The correlation of photosensitivity of resonance signals with luminescence is discussed.