Enhancement of X129e polarization by off-resonant spin exchange optical pumping

Abstract

A high power narrow line width (38 W, 0.09 nm full width at half maximum) external cavity diode laser is investigated for rubidium spin exchange optical pumping of X129e. This tunable photon source has a constant line width, independent of operating power or wavelength within a 1 nm tuning range. When using this laser, an increase in the X129e nuclear polarization is observed when optically pumping at a lower wavelength than the measured Rb electron D1 absorption. The exact detuning from D1 for the highest polarization is dependent upon the gas density. Furthermore, at high power and/or high Rb density, a reduction in the polarization occurs at the optimum wavelength as previously reported in spin exchange optical pumping studies of H3e which is consistent with high absorption close to the cell front face. These results are encouraging for moderate high throughput polarization of X129e in the midpressure range of (0.5–2.0 amagat).