Level-Crossing Determination of the(6s6p)P13hfs ofHg203

The level-crossing technique has been used to measure the hyperfine structure of 47-day ${\mathrm{Hg}}^{203}$ and to remeasure the $g_J$ value of ${\mathrm{Hg}}^{199}$ in the $\mathrm{}\left(6s6p\right)\mathrm{}{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ atomic state. The results, corrected for second-order perturbations arising from other fine-structure levels of the configuration, are $A=4991.\mathrm{}35\left(3\right)\mathrm{}$ MHz, $B=-249.\mathrm{}2\left(3\right)\mathrm{}$ MHz, $g_J=1.\mathrm{}486110\left(9\right)\mathrm{}$, and $\frac{A\left({\mathrm{Hg}}^{203}\right)}{A\left({\mathrm{Hg}}^{199}\right)}=0.\mathrm{}338301\left(2\right)\mathrm{}$. With these values, we calculate the nuclear moments $\mu =0.\mathrm{}856\left(9\right)\mathrm{}{\mu }_N$ and $Q=0.\mathrm{}46\left(4\right)\mathrm{}$ b. The value of $\mu$ includes a diamagnetic correction but not the calculated effect of the ${\mathrm{Hg}}^{199}$-${\mathrm{Hg}}^{203}$ hfs anomaly, ${}_{}{}^{203}{}_{}{}^{}\Delta _{}^{199}{}_{}{}^{}\approx -0.\mathrm{}91\%$. The error brackets for $\mu$ and the hfs interaction constants allow for a hfs anomaly of ±1%. The value of $Q$ does not include the Sternheimer correction. Formulas are given for the dependence on geometry and polarization of level-crossing signals, and a method of correction for asymmetric line shapes is described. The influence of variation, over a large range, of $\frac{B}{A}$ on the magnetic field positions of the level crossings for $J=1\mathrm{}$ has been studied. For $A=0\mathrm{}$ and neglecting the $g_I$ term in the Hamiltonian, the energy displacement from the "center of gravity" and the magnetic field position of the single level crossing are shown to be ${\sigma }_c=-\frac{A}{2}$, and $H_c=\frac{\mathrm{}(2I+1)\mathrm{}\left|A\right|\mathrm{}}{2{\mu }_B{g}_J}$, respectively.