E0(g)(+) -> A 1(u) and E0(g)(+) -> B '' 1(u) laser-induced fluorescence inmolecular iodine recorded by Fourier-transform spectroscopy

The E 0(g)(+) --> A 1(u)((3)Pi(u)) and E 0(g)(+) --> B " 1(u)((1)Pi(u)) flu orescence has been recorded at moderate resolution (0.150 cm(-1)) in the ra nge 28600-31600 cm(-1), using the direct optical-optical double resonance: E 0(g)(+) <-- B 0(u)(+) <-- X 0(g)(+). Both the 1(u) states observed in flu orescence correlate with ground-state I atoms. The Omega-type doubling obse rved in these states is interpreted in terms of their interactions with the two 0(u)(-) states dissociating at the same limit. This is the first rotat ional analysis of the weakly bound B " 1(u) state, The equilibrium spectros copic constants are T-e = 12344,804(40) cm(-1), omega(e) = 19.83(3) cm(-1), B-e = 0.014607(11) cm(-1) and r(e) = 4.265 Angstrom. The last observed vib rational level is v " = 20 which Is located 0.978 cm(-1) below the dissocia tion limit. The parameters describing the long-range part of the potential curve are D-e (B " 1(u)) = 202.53(4) cm(-1), C-5 = -0.49(28) x 10(5) cm(-1) Angstrom(5), C-6 = 1.00(33) x 10(6) cm(-1) Angstrom(6), C-8 = 0.40(6) x 10 (8) cm(-1) Angstrom(8). The last bound vibrational level is v = 23(-1)(+0). In addition a self-induced electronic collision transfer [GRAPHICS] is observed with the strong propensity rule J(t) = J' +/- 1 and a vibration al propensity v' --> v(t) governed by the proximity of the resonance betwee n the energy loss in D 0(u)(+)(v(t),J(t)) and the energy separation (J " - J(t)" similar to 0) of rovibrational levels of the X 0(g)(+)(v ",J ") partn er in the collision. (C) 1999 Elsevier Science B.V. All rights reserved.