Table 2. Assignment of IR vibrations of propanal on Pd(111) at 120 K.

Mode	IR frequency/cm–1			Ref./cm–1
	Sub-monolayer	Near monolayer	Multilayer
ν a(CH3)	2960	2970	2987	2992–2985, 20 2980, 21 2982–2980 22
ν a(CH2)	2943	2943	2943	2954–2941, 20 2941–2939 22
ν s(CH2)			2904	2914–2901, 20 2909–2899 22
ν s(CH3)	2876		2884	2905–2883, 20 2880 21
ν(CH)			2868 a	2774–2712 + 2867–2818 20
			2752 a	2700 + 2800 21
				2850–2700 23
2δ(CH)				2718 + 2772 24
ν(C O)	1560	1663	1728/1695	1580 (Cu-acetylacetone) 37
				1595, 1562 (carboxylate) 38
				1569 b (acrolein/Pt-Ni) 39
				1565 (CO2 –) 40
				1740–1720, 12 1754–1729 20 1746, 23 1750 21
δ a(CH3)	1455–1468	1455–1468	1455–1468	1475–1450 12
				1467–1451 20
				1460, 1451 21
δ(CH2)	1413	1413	1413	1425, 12 1423–1413 20 1420 21
δ(CH)	1370	1370	1392	1395, 21 1381–1374, 20 1385, 25 1410–1380 12
δ s(CH3)	1358	1385		1342–1338, 22 1383–1377, 12 1380 21
				1395–1392 20
ω(CH2)			1344	1340 21
τ(CH2)	1270			1261–1250, 20 1250, 21 1260 22
ρ(CH3)	1070	1070	1095	1098–1093 20
ν a(CCC)	990			1001–993 20

^a Fermi resonance.

^b In HREELS measurement.