Electron Paramagnetic Resonance ofNi+andNi3+in ZnSe

Photosensitive electron-paramagnetic-resonance spectra of ${\mathrm{Ni}}^{+}$ and ${\mathrm{Ni}}^{3+}$ substitutional for zinc in ZnSe have been observed. The ${\mathrm{Ni}}^{+}$ $g$ factor is reduced from the crystal-field theoretical value. Interpretation of the reduction in terms of covalent bonding implies considerable delocalization of the nickel wave function; however, a dynamical Jahn-Teller effect may cause the reduction. Superhyperfine structure from the nearest-neighbor seleniums is observed for ${\mathrm{Ni}}^{3+}$.