Spectroscopic constants and vibrational assignment for the B ³∏_0u+ state of iodine

Portions of the iodine B ³∏_0u+←X ¹∑_g+ absorption spectrum have been remeasured under high resolution. A new analysis of 719 lines in the 3-6, 4-7, 5-4, 7-5, 11-1, 12-2, 13-2, 25-0, and 29-0 bands, combined with previous measurements by Mecke, Loomis, and Brown, gives the following revised constants: ω _e′=125.273 cm^-1 T_e′=15770.59 γ_e′=-4.0×10^-7 ω_ex _e′ = 0.7016 B_e′ = 0.028969 δ_e′=-3.5×10^-8 ω_ey _e′=-0.00567 r_e′ = 3.0276 Å D _e′ = 3.5×10^-9 w_eZ _e′ = +0.000032 α_e′ = 0.0001562 β_e′ = 3.9×10^-10 D_e′ = 4391.0 Constants for ground state rotational levels were found to be in good agreement with Rank's latest determinations. Using these new constants for the B state, Franck-Condon factors for this system were computed. The vibrational numbering originally assigned by Mecke and Loomis to the B state was decreased by one unit to bring calculated intensity distribution into complete agreement with all observed fluorescence data, including new photoelectric measurements on a number of bands. No systematic variation of the electronic transition moment could be derived from these data. These revised Franck-Condon factors were also used to recalculate radiative lifetimes from absolute absorption data which are in fair agreement with the phase-shift determination of Brewer, Berg, and Rosenblatt.