The visible absorption spectrum of ¹⁶OBr¹⁶O and ¹⁸OBr¹⁸O isolated in solid Ne

The visible absorption spectrum of OBrO isolated in solid Ne is recorded in the 15 800-20 500 cm^-1 region. Unlike that reported previously for OBrO in solid Ar, the spectrum in solid Ne has sharp zero-phonon lines (ZPL) exhibiting short progressions of bending (ν₂′) mode built upon a long progression of symmetric stretching (ν₁′) mode. Use of ¹⁸O isotopic labeling resolves discrepancies in vibrational assignments proposed previously. Fitting of the wavenumbers of ZPL yields T₀ = 15 818.4 ± 0.2, ω₁′ = 642.77 ± 0.13, ω₂′ = 223.21 ± 0.43, x₁₁′ = -2.85 ± 0.01, x₂₂′ = -1.07 ± 0.13, and x₁₂′ = -2.49 ± 0.04 cm^-1 for the C²A₂ - X²B₁ transition of ¹⁶O⁷⁹Br¹⁶O and T₀ = 15 832.0 ± 0.2, ω₁′ = 612.49 ± 0.12, ω₂′ = 214.01 ± 0.39, x₁₁′ = -2.61 ± 0.01, x₂₂′ = -1.28 ± 0.12, and x₁₂′ = -2.63 ± 0.04 cm^-1 for ¹⁸O⁷⁹Br¹⁸O. A weak line at 16744.3 cm^-1 may be assigned as 3₀² to yield 2ν₃ = 925.7 cm^-1 for ¹⁶O⁷⁹Br¹⁶O. Observed spectral parameters agree well with high-level theoretical predictions by Peterson.