Table 2.

Principal contributions in SERS spectrum of human tears and their assignment according to Refs. [12,21,22].

nr	Center (cm${}^{-1}$)	Assignment	Component
1	484	Ring def.	amino acids
2	645	COO${}^{-}$ wag.	amino acids
3	730	COO${}^{-}$ def.	amino acids
4	855	C-C str.	amino acids
5	944	C-C str.	amino acids
6	1000	symm. ring CC str.	phenylalanine
7	1121	NH${}_3^{+}$ def.	amino acids
8	1165	N-H wag.	amino acids
9	1243	Amide III $\beta$-sheet, CH${}_2$ wag.	protein
10	1291	Amide III $\alpha$-helix CH${}_2$ wag.	protein
11	1342	C-H def.	Aspartic acid, amino acids
12	1435	CO${}^{-}$ symm. str.	Glutamic acid, amino acids
13	1533	C-C str.	amino acids
14	1567	NH${}_2$ sciss.	amino acids
15	1624	Indole N-H, C=O str.	amino acids
16	1661	Amide I $\alpha$-helix	protein

(def.: deformation; wag.: wagging; str.: stretching; sciss.:scissoring).