Paramagnetic Resonance Investigation of Irradiated KCl Crystals ContainingU-Centers

The effects of ultraviolet irradiation of KCl—KH and KCl—KD single crystals at 80°K and 300°K have been investigated using paramagnetic resonance and optical absorption techniques. KCl—KH crystals irradiated at 80°K have been found to exhibit, along with the usual $F$-center spin resonance, a resonance doublet with a splitting of 500±10 gauss and a line width of 68±5 gauss; the doublet is presumed to be due to hydrogen atoms in the crystal. This conclusion is substantiated by the fact that KCl—KD crystals, after a similar irradiation, exhibit a resonance triplet with a separation of outer components of 156±10 gauss. Further results lead to the following conclusions: (1) that the hydrogen atoms produced by irradiation are located in interstitial positions in the lattice, (2) that these interstitial hydrogen atoms give rise to an optical absorption band ($U_2$-band) located at 236 mμ, (3) that a broad optical absorption band ($U_1$-band) extending to the long wavelength side of the $U$-band is due to interstitial hydride ions.