Raman imaging reveals in-situ microchemistry of cuticle and epidermis of spruce needles

Table 1 Assignment of different components of the cuticle. Wavenumbers derived from NMF

Wavenumber (cm⁻¹)			Assignment
Wax	Cutin	CaOx	Assignment
1734	1723		ν C=O (fatty acid esters)
1712	1707		ν C=O (coumaric acid, midchain carbonyls)
	1654		ν C=C (anthoxanthins)
1632	1634		ν C=C (coumaric acid, stilbenes); Φ8 (anthoxanthins)
1607	1607		Φ8 (all rings)
	1570		ν C=O (anthoxanthins)
		1488	ν C=O (Calcium oxalate) [107]
		1463	ν C=O (Calcium oxalate) [107]
1455			δ C–H (aliphatic chains) [57]
1441	1440		δ C–H (aliphatic chains) [57]
1423			δ C–H (aliphatic chains) [57]
1372			γ_w CH₂ (aliphatic chains) [57]
	1362		Φ20a (anthoxanthins(A-ring))
	1308		γ_t CH₂ (aliphatic chains) [57]
1295			γ_t CH₂ [57]
1201	1205		Φ7a (coumaricacid)
	1177		Φ9a (anthoxanthins with p-subst. C-Ring)
1169			Φ9a (coumaric acid)
1123			ν C–C (aliphatic chains)
	1112
	1077		ν C–C (aliphatic chains)
1062	1066		ν C–C (aliphatic chains)
	1001		Φ12 (stilbenes)
921			ν C–C (aliphatic chains)
		895	ν_s C–C + δ O–C=O (Calcium oxalate) [107]
864	870	864	ν C–C + γ_r CH₂ (aliphatic chains) [108]; (Calcium oxalate)
	831		ν C–C + γ_r CH₂ (aliphatic chains) [108]
	738		(Kaempferol)
710
653
642	642		Φ6a (anthoxanthins (A-ring))
		593	Water libration (Calcium oxalate) [107]
	582		Φ1 (anthoxanthins (A-ring))
524		520	ν Ca-O + ν C–C (Calcium oxalate) [107]
	518		Φ6b (anthoxanthins (A-ring))
		503
418	414

ν: stretching; δ: bending; γ_t: twisting; γ_r: rocking, γ_w: wagging; Φ: ring mode in Varsanyi notation [59]

ISSN: 1746-4811