Rotational assignments in excited iodine and reorientation by elastic and inelastic collisions from circularly polarized emission

We report the circular polarization of two of the resonance fluorescence series from excited molecular iodine, prepared by excitation with the 5145 Å and 5017 Å lines of an argon laser. The sign of the circular polarization of the rotationally resolved features is used to assign the spectrum. In addition, the circular polarization measures the populations of the MJ states in the excited molecule and we describe experiments to investigate the dependence of this polarization on foreign gas pressure and laser power. Results suggest that there is a strong persistence of the initially selected distribution of MJ states throughout elastic and rotationally inelastic collisions.