10min:
FOURIER TRANSFORM SPECTRA OF THE A 2 Pi-X 2 Sigma+ TRANSITION OF MgBr NEAR 380 NM.

T. HIRAO AND P. F. BERNATH, Centre of Molecular Beam and Laser Chemistry, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

It is well-known that the A 2 Pi state of the magnesium monohalide

radicals (Mg X, X = F, Cl, Br, I) are predissociated. Spectroscopic

results of this predissociation are available, however, only for MgF and

MgCl. In this study, the high-resolution emission spectra of the gaseous magnesium bromide (MgBr) radical have been detected. The spectra of MgBr were recorded by using Bruker IFS120HR Fourier transform

spectrometer, modified to record double-sided interferograms. The MgBr radical was generated in the microwave discharge of Ar buffer gas (1.5 Torr) with a trace of the vaporized MgBr2 salt. The vapor of the MgBr2 salt was obtained in a quartz tube heated to about 400oC with a heating tape. The (0,0) and (1,1) vibrational bands

for the A 2 Pi1/2 - X 2 Sigma+ were clearly identified

near 380 nm, but only the (0,0) sub-band for the A 2 Pi3/2 - X 2 Sigma+ was detected, probably due to a predissociation. The assignment is in progress.