Table 6. Anharmonic fundamentals ^{a, b, c} (in cm ^-1) and intensities (I, in km/mol) ^d .

CH 3CO
			Calc.	I	Obs. e [Ref]
ν( a’)	ν 1	CH 3 st	2988	4.80	2989.1 (19) 20
	ν 2	CH 3 st	2919	3.25	2915.6(29) 20
	ν 3	CO st	1900	182.79	1880.5 (100) 20 ; 1875 17 ; 1842 18
	ν 4	CH 3 b	1427	18.41	1419.9(80) 20 ; 1420 17
	ν 5	CH 3 b	1331	14.82	1323.2(109) 20 ; 1329 17, 18
	ν 6	HCC b	1021	16.21
	ν 7	CC st	833	5.03	836.6(45) 20
	ν 8	OCCb	464	5.86	468.1(28) 20
ν( a”)	ν 9	CH3 st	2997	0.17	2990.3(42) 20
	ν 10	CH 3 b	1429	7.23	1419.9(80) 20
	ν 11	CH 3 b	931	0.03
	ν 12	CH 3 tor	82	0.95
CH 2CHO
ν( a’)	ν 1	CH st	1.04	3133
	ν 2	CH st	3035	0.93
	ν 3	CH st	2813	53.34	2827.91 21
	ν 4	CCO st	1465	282.82	1528 22– 26
	ν 5	CH 2 b	1435	5.98	1486 25
	ν 6	OCH b	1365	3.76	1376 24, 25
	ν 7	CC st	1132	56.06	1143 22, 23, 25– 27
	ν 8	CC st	950	9.75	957 25
	ν 9	CCO b	495	15.13	500 22, 23, 25– 27
ν( a”)	ν 10	H 4 wag	954	4.57	703 25
	ν 11	CH 2 wag	729	33.77	557 25
	ν 12	CH 2 tor	402	1.05	402(4) 25
CH 3COCH 2
ν( a’)	ν 1	CH 2 st	3145	1.72
	ν 2	CH 3 st	3074	4.61
	ν 3	CH 2 st	3040	0.87
	ν 4	CH 3 st	2927	0.34
	ν 5	CO st	1541	472.48	1554.1 16 , 1558.9 16
	ν 6	CH 3 b	1449	14.76
	ν 7	CH 2 b	1440	17.36	1419.32 16
	ν 8	CH 3 b	1365	51.02	1377.51 16
	ν 9	CCH b	1243	91.05	1247 28
	ν 10	CCH b	1051	3.87
	ν 11	CCH b	910	14.21
	ν 12	CC st	813	1.67
	ν 13	OCC b	521	15.98	515 28
	ν 14	CCCb	385	2.96
ν( a”)	ν 15	CH 3 st	2971	1.67
	ν 16	CH 3 b	1440	6.25
	ν 17	CH 3 b	1001	8.34
	ν 18	CH 2 wag	732	28.32
	ν 19	CH 3 b	500	1.18
	ν 20	CH 2 tor	343	0.04
	ν 21	CH 3 tor	77	0.18

a st= stretching; b=bending;wag=wagging; tor=torsion.

b 16– 18 Measured in Ar matrix; 20 in pH ₂ solid; 21– 28 in the gas phase.

c Emphasized in bold transitions for which important Fermi displacements are predicted.

d Intensities of the absortion transition lines from the ground state to the fundamental bands calculated using VPT ₂.

e Experimental uncertainties, when available, are given in parentheses in units of the last quoted digit.