Table 2 Sugarcane cell wall vibrational modes and spectral assignments

967

Arabinoxylan [26]

991

C–O stretch [35]

1006

C–O and C–C stretch, and CH₂ rock in cellulose [36]

1016

Pectin [27]

1026

C–O, C–O–H, C–O–C, C–C, ring stretching vibration in cellulose and hemicellulose [30, 37, 38]

1035

Aromatic C–H in-plane deformation (lignin) [19, 39];

C–C, C–O, C–C–O, C–O–C, C–O–H stretch in cellulose and hemicellulose [19, 37, 40, 41]

1040

C–C, C–O, C–O–C, C–O–H stretching vibration in cellulose and hemicellulose [19, 37]

1053

C–O stretch, C–O, C–C ring [19, 41]

1062

Glycosidic linkage in cellulose [28]

1104

C–O–H, C–O–C, C–C, ring stretching vibration in cellulose [19, 37, 41];

OH band in cellulose and hemicellulose [19, 38, 41]

1110

O–H band in cellulose and hemicellulose (crystalline cellulose); cellulose anti-symmetrical stretch [35]

1123

C–O, C–C stretching in starch [29]

1159

C–C, C–O, C–O–C, C–O–H stretching vibration in cellulose [19, 37, 40–42];

Anti-symmetrical bridge oxygen stretching [35]

1173

C–O–C, C–C stretch in xylan [30]

1249

Aryl ring breathing mode; C–O stretch (lignin) [19, 35, 41];

C–O stretch in hemicelluloses [19, 41, 42]

1315

C–H ring, CH₂ symmetrical wagging, O–H in-plane bending [19, 35, 42]

1339

O–H in-plane bending and CH in cellulose and hemicellulose [35, 40, 42]

1374

C–H bending in cellulose [35];

C–H, CH₂ bending in hemicellulose [19, 41]

1419

CH₂ scissoring at C(6) in cellulose [38];

C–H deformation in hemicellulose [19, 41]

1458

O–H in-plane bending in cellulose [35];

CH₃ asymmetrical bending (lignin) [19, 39, 41]

1497

Aromatic ring vibration [43]

1509

C=C stretching vibration in aromatic ring of lignin [19, 38, 39, 41]

1541

N–H in amide II [44, 45]

1639

C=C, conjugated or aromatic carbonyl groups [46]

1647

C–O stretching vibration in lignin [41]

1716

C=O stretch in lignin [19]

1722

C=O stretch in lignin [19]

1733

C=O stretching vibration in acetyl groups of hemicellulose [38, 40–42]