ELECTRONIC STATES OF THE BI2 MOLECULE

The thermal emission spectrum of Bi2 in the region 3500 to 9000 cm-1 h as been recorded by Fourier transform spectrometry, and laser-induced fluorescence spectra of Bi2, excited by lines of an argon-ion laser, h ave also been recorded. The dense thermal emission spectrum consists p redominantly, if not entirely, of lines of a system al(u)(3SIGMA(u)+)- X0g+. The state al(u) is the lower state of a system observed in LIF a nd originally labelled E-B. Vibrational and rotational constants are d erived for the states involved. Measurement of the small OMEGA-doublin g in al(u) allows an estimate of the (0u--1u) separation in a 3SIGMA(u )+ to be made: it is 4540 cm-1.