The Rotational Analysis of the A2Πr–X2Σ+ Band System of MgBr

✍ Scribed by T. Hirao; B. Pinchemel; P.F. Bernath

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 174 KB
• Volume: 202
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.2000.8139

✦ Synopsis

The A 2 ⌸ r -X 2 ⌺ ϩ emission spectrum of the magnesium monobromide radical, MgBr, has been recorded with a Fourier transform spectrometer modified to record double-sided interferograms. The emission spectra of the ⌬v ϭ Ϫ2, Ϫ1, 0, ϩ1 bands were generated in a microwave discharge of a mixture of argon and vaporized MgBr 2 . The ⌬v ϭ 0 and Ϫ1 bands were rotationally resolved, but the F 2 spin component ( A 2 ⌸ 3/ 2 ) in the (1, 1), (1, 2) and vibrational bands with vЈ Ͼ 1 were missing in our spectra because of a strong predissociation in the A state. The molecular constants in both electronic states were determined for the two bromine isotopomers. The r 0 bond length in the A state is about 2.327 Å, which is about 0.02 Å shorter than in the ground state. Franck-Condon factors were calculated from the Rydberg-Klein-Rees potentials, and they reproduce the observed relative intensities of the bandheads. An upper limit for the dissociation energy (D 0 0 ) was obtained as 26 268.4 cm Ϫ1 , based on the absence of the energy level with v ϭ 1, A 2 ⌸ 3/ 2 , J ϭ 1.5 in our spectrum.