INTERCOMBINATION TRANSITIONS B(3)PI(U)[-CHI(1)SIGMA(-2()(G) IN NA)

The weak intercombination band b (3) Pi(u)(upsilon(b) = 0) <-- X (1) S igma(g)(+)(upsilon '' = 0) of Na-2 molecules formed in a supersonic be am has been excited directly with a pulsed narrow-band dye laser and r ecorded with rotational resolution, Molecular constants of the b (3) P i(u) state are derived and compared with results in the literature, ob tained with other techniques. The different perturbation mechanisms ar e discussed. (C) 1997 Published by Elsevier Science B.V.