Fourier transform spectroscopy of the 1 3Σ+g–a 3Σ+u transition of the 6Li2 molecule

The 1 3Σ+g–a 3Σ+u transition of 6Li2 has been observed via collisionally induced fluorescence, excited by visible lines of an argon-ion laser and detected at high resolution with a Fourier–transform spectrometer in the 8200–10 100 cm−1 region. By combining the results with previously obtained data on 7Li2 F. Martin, R. Bacis, J. Vergès, C. Linton, G. Bujin, C. H. Cheng, and E. Stad, Spectrochim. Acta Part A 44, 1369 (1988), an accerate, isotopically consistent description of both states has been obtained for 1≤v′≤7 and 0≤v″≤7. Equilibrium constants, Rydberg-Klein-Rees potential curves, and dissociation energies have been determined and found to be in good agreement with ab initio calculations. From the analysis, the following positions and dissociation energies of the two states were found. For 1 3Σ+g, Te (cm−1) is 16 328.8(1.7) and De (cm−1) is 7091.6(1.2). For a 3Σ+u, Te (cm−1) is 8183.8(1.5) and De (cm−1) is 333(1).