Table 2. Measured wavelength and calculated wavenumbers of the bands found with PCA, SIMCA, OPLS-DA and PLSR methods and their assignment based on the corresponding references.

Measured wave-length (nm)	Calculated wave-number (cm−1)	Calculated fundamental wavenumber (cm−1)	Assignment	Ref
1155		-	Combination overtone of free water (S0)	-
1365	7326	7326/2 = 3663	OH, 1st overtone, aqueous proton [H+·(H2O)2]—H2O asymmetric stretch	[40]
			OH, 1st overtone, Dangling-OH (non-hydrogen-bonded	[41]
			OH, 1st overtone, H2O v1	[42]
			OH, 1st overtone, H15O7+	[43]
1386	7215	7215/2 = 3607.5	OH, 1st overtone, Superoxide Tetrahydrate O2-.(H2O)4	[44]
			OH, 1st overtone, H+(H2O)10	[40]
			C–H stretching, sucrose	[45]
			OH, 1st overtone, OH- stretching mode	[46]
1408	7100	7100/2 = 3550	OH, 1st overtone, H-bonded OH stretch	[47]
			O–H, 1st overtone, glucose bonds	[48]
			OH, 1st overtone, OH stretching in alcohols	[49]
			OH, 1st overtone, hydrogen-bonded dimers	[50]
1450	6895	6895/2 = 3447.5	OH, 1st overtone, deionized water	[51]
			OH, 1st overtone, O-H stretch	[52]
			combination of antisymmetric and symmetric stretching modes of water	[53]
1485	6735	6735/2 = 3367.5	OH, 1st overtone, H17O8+	[43]
			OH, 1st overtone, H15O7+ H-bonded OH stretch	[47]
			NH, 1st overtone, amid	[54]
			NH/OH, 1st overtone, N–H/O–H stretching	[55]
1492	6700	6700/2 = 3350	OH, 1st overtone, hydrogen-bonded (S4)	[34]
			OH, 1st overtone, H15O7+	[43]
			OH, 1st overtone, strongly H-bonded	[56]
			NH, 1st overtone, N–H stretching	[57,58]
			NH, 1st overtone, NH2's asymmetric stretch	[59]
1698	5890	5890/2 = 2945	OH 1st overtone, Superoxide Tetrahydrate O2-.(H2O)4	[44]
			C−H vibration	[60]
			CH/CH2 combination band	[61]
			H–O–H/O–H bending and translation/rotation combinations	[62]
1819	5500	5500/2 = 2750	1st overtone IHB stretch (OH-(H2O)3)	[63]
			combinationν(C−H) + ν(O−D)free	[64]