FCenters in SrO and the Quadrupole Moment ofSr87

The paramagnetic resonance spectrum of $F$ centers in single crystals of SrO is reported. The isotropic part of the hyperfine interaction $A$ is 14.65±0.08 G for the nearest-neighbor ${\mathrm{Sr}}^{87}$ nuclei, and the dipolar hyperfine interaction constant $B$ is 1.55±0.03 G. Quadrupole-moment effects are prominent in the spectrum and we find $\frac{\mathrm{Qq}{e}^2}{h}=46\mathrm{}\pm 4$ Mc/sec. Without detailed calculation, we find a value for the electric field gradient which is sufficiently accurate to allow us to quote $Q=0.15\mathrm{}\times {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ for ${\mathrm{Sr}}^{87}$ with an uncertainty of no more than 40%. The values of $A$ and $B$ are correlated rather well with the values measured in other II-VI compounds by an extension of the analysis used for $F$ centers in the alkali halides.