Vibrational analysis of the A' 1Π state of barium oxide using two isotopes

Barium vapor is reacted with N₂¹⁶O and N₂¹⁸O at 0.7 Torr to produce clearly distinguishable isotopic bands of BaO A' ¹Π- X¹Σ in the wavelength region of 320-415 nm. The unique vibrational numbering is determined by measuring the isotopic shift in the bandheads between Ba ¹⁶O and Ba ¹⁸O. Spectroscopic constants for the A' ¹Π state are determined from the present analysis to be ν₀₀ = 17 588 ± 15 cm ^-1, ω_e = 442.45 ± 0.3 cm ^-1, and ω_ex_e = 1.652 ± 0.009 cm ^-1. Uncertainties represent three standard deviations.