The Process of Energy Transfer between Excited Sodium Atoms

Two experiments were carried out to test a process proposed by Allegrini et al. as a viable explanation of the fluores cence from high lying levels which is observed when sodium vapor is illuminated by resonance radiation In the first experiment a cell with sodium vapor was illuminated by a cw dye laser tuned to the 3s * 3P transition, and the linewidth and lmeshape of the fluorescence from the 3D I+ 3P transition were measured. In the second experiment the cell was illuminated by two pulsed lasers, one tuned to the 3s + 3P resonance and the second well off resonance with this tram& tion. The photoionization current was measured, as was the fluorescence intensity from the 65 * 3P and SD + 3P transitions, We conclude that the Allegrini process does not significantly contribute to the populations in the SD, 6s and 3D states.