Infrared measurements of BrO (X²Π _{3 2})

The v = 1-0 band of BrO in the X²Π _{3 2} spin state was measured using high-resolution Fourier transform absorption spectroscopy. One hundred and thirty transitions were assigned and analyzed to determine the band origins, rotational constants, and distortion constants for both ⁷⁹BrO and ⁸¹BrO. The v = 1-0 band strength was determined to be 5.04 ± 0.80 cm^-2 atm^-1 using a Herman-Wallis type analysis. The A²Π-X²Π transition of BrO was measured in the region 285 to 355 nm simultaneously with the infrared measurements with a diode array spectrometer. UV absorption cross sections of the A²Π-X²Π transition were determined relative to the calculated IR intensities. The absorption cross section at the peak of the (7, 0) band at 338.5 nm is (1.4 ± 0.3) × 10^-17 cm² molecule^-1 at 298 K.