Level-crossing determination of the (6s6p)P13 hfs of Hg203

The level-crossing technique has been used to measure the hyperfine structure of 47-day Hg203 and to remeasure the gJ value of Hg199 in the (6s6p)P13 atomic state. The results, corrected for second-order perturbations arising from other fine-structure levels of the configuration, are A=4991. 35(3) MHz, B=-249. 2(3) MHz, gJ=1. 486 110(9), and A(Hg203)A(Hg199)=0. 338 301(2). With these values, we calculate the nuclear moments μ=0. 856(9)μN and Q=0. 46(4) b. The value of μ includes a diamagnetic correction but not the calculated effect of the Hg199-Hg203 hfs anomaly, Δ199203-0. 91%. The error brackets for μ 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 BA on the magnetic field positions of the level crossings for J=1 has been studied. For A=0 and neglecting the gI 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 σc=-A2, and Hc=(2I+1)|A|2μBgJ, respectively.