Cross-section measurement and theoretical evaluation for the energy-transfer collision Na(3P)+Na(3P)→Na(4F)+Na(3S)

We have measured the cross section {σ}(4F) for the collisional process Na(3P)+Na(3P){→}Na(4F) +Na(3S). The experiment is based on the measurement of the intensities for 4F, 4D, and 3P fluorescence emissions in sodium vapor excited with a cw dye laser. {σ}(4F) is determined relative to {σ}(4D), which has been measured in an absolute way in previous experiments. Influence on {σ}(4F) and {σ}(4D) of the energy-transfer process Na(4F) +Na(3S){}Na(4D)+Na(3S) is also discussed. A theoretical evaluation of {σ}(4F) and {σ}(4D) relative to a chosen molecular channel is given and compared with the experimental determinations.