The rotational analysis of the A(2)Pi(r)-X-2 Sigma(+) band system of MgBr

The A(2)Pi-X(2)Sigma(+) emission spectrum of the magnesium monobromide radi cal, MgBr, has been recorded with a Fourier transform spectrometer modified to record double-sided interferograms. The emission spectra of the Delta v = -2, -1, 0, +1 bands were generated in a microwave discharge of a mixture of argon and vaporized MgBr2. The Delta nu = 0 and -1 bands were rotationa lly resolved, but the F-2 spin component (A(2)Pi(3/2)) in the (1, 1), (1, 2 ) and vibrational bands with nu' > 1 were missing in our spectra because of a strong predissociation in the A state. The molecular constants in both e lectronic states were determined for the two bromine isotopomers. The r(o) bond length in the A state is about 2.327 Angstrom, which is about 0.02 Ang strom shorter than in the ground state. Franck-Condon factors were calculat ed from the Rydberg-Klein-Rees potentials, and they reproduce the observed relative intensities of the bandheads. An upper limit for the dissociation energy (D-o(o)) was obtained as 26 268.4 cm(-1), based on the absence of th e energy level with nu = 1, A(2)Pi(3/2), J = 1.5 in our spectrum. (C) 2000 Academic Press.