Abstract：The B 1Πu electronic state of Na2 was excited by the 441.6 nm He-Cd laser line. The Na atomic transitions and the A 1Σ+u→X 1Σ+g band of Na2 were recorded. From the intensities and spectra of the Na and Na2 fluorescence several collisional processes in the excited sodium atom-dimer system were identified. The Na atomic lines are the result of collisional energy transfer from Na2(B 1Πu) to Na(3P). Predissociation process may also contribute to atomic fluorescence. The A 1Σ+u→X 1Σ+g band is interpreted through a populating mechanism involving collisional transfer from B 1Πu to 2 1Σ+g followed by a radiative transfer to the A 1Σ+u state. From the decay constants and fluorescence intensities, the rate coefficient at 360 ℃ for collisional energy transfer from Na2(B 1Πu) to Na2(2 1Σ+g) was found to be 5.7×10-10 cm3·s-1. The predissociation rate of the B 1Πu is 2.7×106 s-1.
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