High-resolution infrared study of Coriolis resonances in the ν9 and ν10 bands of allene-d4

The infrared perpendicular bands ν₉ and ν₁₀ in allene-d₄, which are located at 824 and 666 cm^?1, respectively, have been studied at a resolution near to 0.010 cm^?1. The bands were analyzed by taking into account the z-Coriolis resonance between these bands and the (x,y)-Coriolis resonance between ν₁₀ and ν₄(B₁), which is only Raman active. Upper-state parameters and interaction constants are derived from this analysis. Additional Coriolis interactions between ν₉ and ν₃(A₁) as well as between ν₁₀ and 2ν₁₁²(B₁,B₂) are also discussed. Special attention is paid to the study of l-type doublings. Doublets due to q^(?) doubling were resolved both in ν₉ and in ν₁₀. l-type doubling constants including their signs are also obtained.