Collisional redistribution of light: Far-wing line shapes and polarizations for the Ba-(Ar,Xe) systems

We have measured the far-wing collisional redistribution line shape, the redistributed fluorescence polarization, and the collisional alignment decay rates for barium perturbed by argon and xenon. The experiment was performed with a heated gas cell ($T\sim 900$ K) with perturber-gas densities in the 1—30-Torr range and laser light detuned ± 3— 1000 ${\mathrm{cm}}^{-1\mathrm{}}$ from the 5535-Å Ba I $6{}_{}{}^1{}_{}{}^{}S-6\mathrm{}{}_{}{}^1{}_{}{}^{}P$ resonance line. Metal-vapor densities were determined by a Rayleigh scattering technique, which is outlined in detail. By correlating structure in the line shape with that of the polarization, we are able to make definitive statements about the interatomic potentials. The Ba data show strong similarities with previous experimental results for similar two-electron atoms, namely Ca, Sr, and Hg, and so our conclusions are of relevance to these systems as well.