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

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 T_e=14 531.2 cm ⁻¹, ω_e′=794.0 cm⁻¹, ω_ex_e′=3.23 cm⁻¹, ω_e^″=861.9 cm⁻¹, ω_ex_e^″=2.95 cm⁻¹ for the lower component, and T_e=14 870.4 cm⁻¹, ω_e′=794.9 cm⁻¹, ω_e′=3.3 cm⁻¹, ω_e^″=862.1 cm⁻¹, ω_ex_e^″=3.025 cm⁻¹ for the upper component. Semiempirical calculations predict T_e=15 330.4 cm⁻¹ for the A′ ²Δ_r 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′ ²Δ_3/2 state, and T₀=15 072.0 cm⁻¹, ΔG′_1/2=837.0 cm⁻¹ for the ScO A′ ²Δ_5/2 state.