Fourier Transform ultraviolet spectroscopy of the A 2Π3/2 ← X 2Π3/2 transition of BrO

Wilmouth, D. M., T. F. Hanisco, N. M. Donahue, and J. G. Anderson, Fourier Transform ultraviolet spectroscopy of the A 23/2 ← X 23/2transition of BrO. J. Phys. Chem. A103, 8935–8945, 1999.

The first spectra of the A 2Π3/2 ← X 2Π3/2 electronic transition of BrO using Fourier transform ultraviolet spectroscopy are obtained. Broadband vibrational spectra acquired at 298 ± 2 K and 228 ± 5 K, as well as high-resolution rotational spectra of the A ← X 7,0 and 12,0 vibrational bands are presented. Wavenumber positions for the spectra are obtained with high accuracy, and cross section assignments are made, incorporating the existing literature. With 35 cm-1 (0.40 nm) resolution the absolute cross section at the peak of the 7,0 band is determined to be (1.58 ± 0.12) × 10-17 cm2 molecule-1 at 298 ± 2 K and (1.97 ± 0.15) × 10-17 cm2 molecule-1 at 228 ± 5 K. BrO dissociation energies are determined with a graphical Birge−Sponer technique, using Le Roy−Bernstein theory to place an upper limit on the extrapolation. From the ground-state dissociation energy, D0‘‘ = 231.0 ± 1.7 kJ/mol, the heat of formation of BrO(g) is calculated, ΔfH°(0 K) = 133.7 ± 1.7 kJ/mol and ΔfH°(298.15 K) = 126.2 ± 1.7 kJ/mol. Cross sections for the high-resolution 7,0 and 12,0 rotational peaks are the first to be reported. The band structures are modeled, and improved band origins, rotational constants, centrifugal distortion constants, and linewidths are determined. In particular, J-dependent linewidths and lifetimes are observed for the both the 7,0 and 12,0 bands.