Magnetic, Thermal, and Optical Properties of theFCenter in NaH

Thermal and optical bleaching and microwave saturation effects on the isotropic resolved electron paramagnetic resonance hyperfine structure of the $F$ center in NaH have been studied. The results indicate that the thermal bleaching is a monomolecular process with an associated activation energy ${\epsilon }_F=0.38\mathrm{}$ ev. A model similar to the print-out effect in silver halides is proposed for the bleaching mechanism. The wave-length of maximum optical absorption is 3.22 ev. The value of the characteristic spin relaxation time ${\left(T_1{T}_2\right)}^{\frac{1}{2}}$ is 1.7×${10}^{-6\mathrm{}}$ second. The $g$ value for the $F$-center electron is 2.0025±0.0003.