Complex Hyperfine Structure in the EPR Spectrum of(FeF6)3−in CdTe

Abstract

The EPR and ${\mathrm{F}}^{19}$ electron-nuclear double resonance (ENDOR) of an ${\left(\mathrm{F}\mathrm{e}{\mathrm{F}}_6\right)}^{3-}$-associated defect in CdTe have been studied. Very well resolved ${\mathrm{F}}^{19}$ hyperfine structure is observed and analyzed in terms of multiple reorientations of ${\mathrm{F}}^{19}$ nuclei. Splittings of the ${\mathrm{F}}^{19}$ ENDOR transitions are interpreted as nuclear spin-spin multiplet structure. The positions and intensities of all observed EPR transitions are in excellent agreement with the calculations. A theory of the ENDOR line splittings is presented which accounts for the observed nuclear multiplet structure including the enhancement of the ENDOR line splittings by the cubic crystal-line fields. The hyperfine structure due to ${\mathrm{Fe}}^{57}$ has also been observed. The experimentally determined parameters are $S=\frac{5}{2}$, $g=2.0029\mathrm{}$, ${T_1}^{19}=(+35.50\mathrm{}\pm 0.02)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, ${T_2}^{19}=(+14.66\mathrm{}\pm 0.02)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, $a=(+99.28\mathrm{}\pm 0.05)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, and $\left|A^{57}\right|=10.7\mathrm{}\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$.