Excited-State Mixing in the Optical Pumping of Alkali-Metal Vapors

Abstract

The effect of excited-state mixing on the optical pumping of alkali-metal vapors is considered for the case where the energy separation between the $^{2}P_{\frac{1}{2}}$ and $^{2}P_{\frac{3}{2}}$ first excited states is relatively large, allowing the isolation of mixing effects within a particular $J$ level. Two models for the mixing process are proposed, one a random reorientation of the total electronic angular momentum J, and the other a reorientation of J subject to the selection rule $\ensuremath{\Delta}{m}_{J}=0, \ifmmode\pm\else\textpm\fi{}2$. The probabilities for mixing transitions among $J$-state sublevels have been calculated for an alkali atom of nuclear spin $\frac{3}{2}$, and can be used to calculate the optical-pumping transition probabilities for a vapor subject to any degree of excited-state mixing. Several possible experiments suggested by these calculations are discussed.