Chemiluminescence spectra of ScO and YO: Observation and analysis of the A′ 2Δ–X 2Σ+ band system

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Abstract
A new band system between 6200 and 7500 Å has been observed in the ’’single collision’’ beam–gas chemiluminescent spectrum resulting from the reactions of Sc and Y atoms with O2. A strong, well‐developed system is observed in the YO spectrum resulting from the Y–O2 reaction. A vibrational analysis of two distinct subsystems, each consisting of double‐headed bands (ΔΛ?1), yields Te=14 531.2 cm −1, ωe′=794.0 cm−1, ωexe′=3.23 cm−1, ωe″=861.9 cm−1, ωexe″=2.95 cm−1 for the lower component, and Te=14 870.4 cm−1, ωe′=794.9 cm−1, ωe′=3.3 cm−1, ωe″=862.1 cm−1, ωexe″=3.025 cm−1 for the upper component. Semiempirical calculations predict Te=15 330.4 cm−1 for the A′ 2Δr state of YO. Perturbation calculations predict that mixing of the A 2Π state with the A′ 2Δ state of YO may be as large as 3.5%. On the basis of these calculations, the new band system is attributed to the A′ 2Δ–X 2Σ+ transition of YO. The new band system in the Sc+O2 spectrum is weaker and not as well resolved as the YO system. However, analysis of the system, by analogy with that of YO, yields T0=14 965.9 cm−1, ΔG′1/2 =834.0 cm−1 for the ScO A′ 2Δ3/2 state, and T0=15 072.0 cm−1, ΔG′1/2=837.0 cm−1 for the ScO A′ 2Δ5/2 state.