Modeling polarization reversal in optically pumped rubidium vapors

Rubidium atoms can be polarized by optical pumping with a resonant circularly polarized laser beam. Using Faraday rotation polarimetry [1], we have observed a flip in the sign of the Rb electron polarization when the wavelength of the pump laser is varied over the D1 absorption spectrum. This could occur if F $<$ (I + J) states with M$_{F}$ = F are predominantly populated at specific pump frequencies resulting in different spin polarizations. We have used a simple rate equation model to estimate the final electron polarization under the assumption that we are able to pump only one F transition at a time. The results of these calculations will be presented. \\[4pt] [1] H. Batelaan, A.S. Green, B.A. Hitt, and T.J. Gay, Phys. Rev. Lett. \textbf{82}, 4216 (1999).