Table 10A. Low-lying vibrational energy levels (in cm ^-1) ^a of the CH ₃CO, CH ₂CHO and CH ₃COCH ₂ radicals computed variationally or using the vibrational second order perturbation theory.

Variational energy levels are classified using the m, n and l quanta corresponding to the θ ₁, θ ₂, and α coordinates according to the excitation energy. The irreducible representations are given according to the MSG G ₆, G ₄ and G ₁₂, respectively.

CH 3CO (G 6)					CH 2CHO (G 4)
m	Variational		VPT2		n l	Variational		VPT2		Exp. [Ref]
0	A 1 E	0.0 2.997	ZPVE	-	0 0	A + B +	0.000	ZPVE	-
1	A 2 E	104.265 76.656	ν 12	82	1 0	A - B -	398.436	ν 12	402	402±4 33
2	A 1 E	132.180 185.760	2ν 12	169				ν 9	495
3	A 2 E	379.440 272.324	3ν 12	261	0 1	A - B -	745.727	ν 11	729	557 33
4	A 1 E	379.849 507.146	4ν 12	358	2 0	A + B +	792.306	2ν 12	782
			ν 8	464				ν 12ν 9	893
			ν 12ν 8	549				ν 8	950
5	A 2 E	821.806 654.566	5ν 12	461				ν 10	954
			2ν 12ν 8	639				2ν 9	993
			3ν 12ν 8	734	1 1	A + B +	1123.980	ν 12ν 11	1107
6	A 1 E	821.807 1008.819	6ν 12	-				ν 7	1132
			ν 7	833	3 0	A - B -	1178.128	3ν 12	1140
			ν 11	931				ν 11ν 9	1225
			2ν 8	929				ν 12ν 8	1348
			ν 12ν 7	915				ν 12ν 10	1357
			ν 12ν 11	998				ν 6	1365
						……….
					0 2	A + B +	1495.772	2ν 11	1459

a)      Emphasized in bold transitions where important Fermi displacements are predicted.