Radiation trapping in rubidium optical pumping at low buffer-gas pressures

We have made a systematic study of rubidium optical pumping in a simple cylindrical cell geometry with a high-power 100.3em0exW diode laser array, low magnetic fields, and buffer-gas pressures of less than 500.3em0extorr. We have determined rubidium polarizations experimentally for H₂, N₂, He, and Ar buffer gases, with Rb number densities from 10¹²0.3em0exto0.3em0ex10¹³0.3em0excm^-3. Comparison to a relatively simple optical pumping model allows us to extract useful information about radiation trapping and quenching effects.