Hyperfine structure ofSr87in theP23metastable state

The atomic-beam magnetic-resonance technique has been used to measure the hyperfine structure of the ${}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}$ state of ${}_{}{}^{87}{}_{}{}^{}\mathrm{Sr}$. This metastable state is populated in an electrical discharge located just in front of the oven orifice. The measured frequencies are $\Delta \nu (F=\frac{13}{2}-\frac{11}{2})=1346.497\mathrm{}\left(6\right)\mathrm{}$ MHz and $\Delta \nu (F=\frac{11}{2}-\frac{9}{2})=1170.208\mathrm{}\left(6\right)\mathrm{}$ MHz. Using these transition frequencies the hyperfine interaction constants, corrected for the perturbing interactions due to neighboring fine-structure levels, are $A=-212.765\mathrm{}\left(1\right)\mathrm{}$ MHz and $B=67.215\mathrm{}\left(15\right)\mathrm{}$ MHz. The errors quoted are only those arising from the uncertainty in the experimental data. We have also used these data with the ${}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ hfs separations measured by zu Putlitz to calculate the quadrupole moment $Q=0.335\mathrm{}\left(20\right)\mathrm{}$ b using the antishielding correction estimated by Sternheimer. The error quoted for $Q$ includes the error in Sternheimer's estimate.