The Band System of the CCO Molecule

Abstract

The transient absorption spectrum observed previously (Devillers) in the flash photolysis of carbon suboxide has been studied under high resolution in the region 5000 to 9000 Å and assigned to the CCO radical. A rotational analysis of the 000–000 band near 8580 Å shows conclusively that the electronic transition is [Formula: see text]. From molecular orbital considerations the lower state is assigned as [Formula: see text]. Short progressions involving the stretching vibrations (ν1′ = 0–3, ν3′ = 0–1) have been observed. A Fermi resonance has been found involving ν3′ and 2ν2′. Some sequence bands have been assigned; in particular the 010–010 sequence band clearly shows the Renner splittings expected for the Ã3Πi excited state. A band with a different type of rotational structure has been assigned to the forbidden component 010 3Σ(−) – 000 3Σ−. The rotational analysis of this band is in excellent agreement with the theory of Hougen for the rotational energy levels of a linear molecule in the ν2 = 1 level of a 3Π state.The following molecular constants have been obtained:[Formula: see text]