A new method, suggested by work of Otten, involving Zeeman scanning of an optically pumped vapor has been developed and used to determine the hyperfine structure of 3.5-h ${}_{}{}^{193}{}_{}{}^{}\mathrm{Hg}$ ($I=\frac{3}{2}$) in the $6s6p{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ state, and the isotope shift in the 2537-Å resonance line. The $6s^2{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ ground state is optically pumped via each of the hfs components. The displacements of the ${}_{}{}^{193}{}_{}{}^{}\mathrm{Hg}$ hfs components from ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}$ are found by measuring the magnetic field used to scan the optical-pumping lamp. The resonance is detected optically. The measured values are 83(4), 572(5), and 911(5) mK for the $F=\frac{5}{2},\frac{3}{2}, \mathrm{and} \frac{1}{2}$ components, respectively. The final results are 80(7) and 572(5) mK for the positions of the first two components corrected to account for perturbations caused by the presence of other isotopes. These perturbations are much smaller than the ones encountered in optical spectroscopy because of the selective nature of our detection method. A model calculation for the relevant emission and absorption processes was developed to determine the perturbations. We obtain, with the use of the previously determined $A$ value, the corrected quadrupole interaction constant $B=+15\mathrm{}\left(7\right)\mathrm{}$ mK. The corrected isotope shift of ${}_{}{}^{193}{}_{}{}^{}\mathrm{Hg}$ relative to ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}$ is 383(7) mK. The resulting corrected odd-even staggering parameter, relative to ${}_{}{}^{192}{}_{}{}^{}\mathrm{Hg}$ and ${}_{}{}^{194}{}_{}{}^{}\mathrm{Hg}$, is $\gamma =0.74\mathrm{}\left(30\right)\mathrm{} or 0.56\left(14\right)\mathrm{}$, the two values corresponding to different measurements of the isotope shift of ${}_{}{}^{192}{}_{}{}^{}\mathrm{Hg}$.

• Received 12 September 1973

DOI:https://doi.org/10.1103/PhysRevA.9.593