Infrared measurements on allene and allene-d4

Abstract Several vibration-rotation absorption bands of allene (C 3 H 4 ) and allene- d 4 (C 3 D 4 ) have been measured with high resolution. From measurements of a parallel and a perpendicular band of C 3 H 4 the following constants were obtained: B 0 = 0.2963 2 ± 0.00006 cm −1 , D J = 11. 6 ± 2.4 × 10 −8 cm −1 and D JK = 4. 6 ± 1.8 × 10 −6 cm −1 . The best measurements on C 3 D 4 were for a parallel band at 2790.25 cm −1 for which the values B 0 = 0.2321 4 ± 0.00008 cm −1 and D J = 4. 1 ± 1.9 × 10 −8 cm −1 were obtained. By combining infrared and Raman measurements of ν 8 a value of A 0 = 4.807 ± 0.008 cm −1 was obtained. The resulting bond parameters are r 0 ( CC ) = 1.308 4 ± 0.0003 A , r 0 ( CH ) = 1.087 2 ± 0.0013 A , and 3 H 4 spectra are described.