GJ factor of the lowest P11 and P13 states of Ba; Level-crossing determination of A(P11)μ0gJ(P11) of Hg199

The gJ(P13) and gJ(P11) factors of the (6s6p) configuration in barium have been determined in a double-resonance experiment. The ratio A(P11)[μ0gJ(P11)] of the (6s6p) configuration in Hg199 has been measured in a level-crossing experiment. The results are: gJ(P11,Ba)=1.0039±0.0008, gJ(P13,Ba)=1.4973±0.0007, -hA(P11,Hg199)[μ0gJ(P11,Hg199)]=2523. 0±3.0 G. From the values of A(P11,Hg199) obtained from optical spectroscopy, a value of gJ(P11,Hg) is derived: gJ(P11,Hg)=1.0127±0.0050. We have summarized all lifetime and gJ values for the first excited sp configuration of the group-II elements. With these results, a comparison of the three different methods of calculating the intermediate coupling coefficients is presented and all methods are found to be in excellent agreement. Previous level-crossing results for the lifetime and hfs of Ba137 have been corrected using the presently determined value of gJ(P11). These corrected results are in much better agreement with other experiments. © 1968 The American Physical Society.