| Absorption ranges (cm−1) | Functional groups | Attributions |
| 3200 - 3640 | Hydroxyls (OH) of alcohols, phenols and carboxylic acids | Lignin and cellulose |
| 2840 - 3000 | CH2 and CH3 of alkyl, aliphatic and aromatic groups | Extractables and cellulose |
| 1540 - 1870 | Carbonyls (C=O) of ketones, carboxylic acids and acetyl groups | Hemicellulose |
| 1516 - 1610 | (C=C) of aromatic rings | Lignin |
| 1330 - 1420 | Phenol hydroxyls (OH) | Lignin and carbohydrates |
| 1200 - 1400 | Hydroxyls of phenols and (C-O-C) in aryl alkyl ether | Hemicellulose and lignin |
| 1085 - 1150 | (C-O-C) in pyronose ring | Cellulose |
| 675 - 900 | (C-H) in lignin aromatic rings | Lignin |