LASER SPECTROSCOPY OF THE 3S 2-SIGMA[-P2-PI TRANSITION IN LINE

Measurements of the rotationally resolved absorption spectrum of the Li-6-Ne-20 and Li-7-Ne-20 3s2-SIGMA+ <-- 2p2-II transition have been made. For each isotope, 13 vibrational transitions from the lower 2p2-II (upsilon" = 0,1,2,3) to the upper 3s2-SIGMA+ (upsilon' = 0,1,2,3,4,5) electronic state have been observed and rotationally analyzed. For the 2p 2II state a well depth of 212(5) cm-1 and an equilibrium separation of 4.36(2)a0 have been obtained. Analysis of the 3s 2-SIGMA+ electronic state using an inverted perturbation analysis has revealed that the potential for this state displays, at large internuclear separations, a barrier greater than 60.6 cm-1 above the atomic Li 3s asymptote. The well region has a minimum of 570(7) cm-1 located at 4.11(1)a0. An anomalously large fine-structure constant of A = 2.77(3) cm-1 was determined for the 2p 2II (upsilon" = 0) level.