Lifetime of the First ExcitedP11State of Mg and Ba; hfs ofBa137

Abstract

The lifetime of the first excited ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ state of Mg and Ba has been obtained from the measured width of the zero-field level-crossing signal in the scattering of resonance radiation from an atomic beam of these elements. The results are $\tau \left(\mathrm{Mg}\right)=(1.99\mathrm{}\pm 0.08)\times {10}^{-9\mathrm{}}$ sec and $\tau \left(\mathrm{Ba}\right)=(8.2\mathrm{}\pm 0.2)\times {10}^{-9\mathrm{}}$ sec. These results are compared with previous measurements and in conjunction with other experimental results are used to obtain the intermediate coupling coefficients for the mixing of the ${}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ and ${}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ states. From a measurement of the one observable high-field level crossing in ${\mathrm{Ba}}^{137}$, the dipole coupling constant for the $6s6p{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ state is found to be - 113.2 ±1.0 Mc/sec in good agreement with the results of Jackson and Tuan. The quadrupole moment of the ${\mathrm{Ba}}^{137}$ is calculated to be 0.20×${10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$ from the data of Jackson and Tuan.