Table 2 Assignments of IR absorption bands for the analysed wood based on the literature [31, 46,47,48]
n° Ref | Band cm− 1 | Assignment |
|---|---|---|
1 | 3250 | Hydrogen bonded stretching (OH) |
2 | 2800–2900 | C–H stretching |
3 | 1736 | Unconjugated C=O in ketones, carbonyl, and aliphatic groups of the xylans (hemicellulose) |
4 | 1650 | H–O–H angle vibration of absorbed water and conjugated C–O in the aromatic ring |
5 | 1597 | C–C aromatic skeletal vibration in lignin |
6 | 1505 | C–C aromatic skeletal vibration in lignin |
7 | 1462 | Asymmetric C–H deformation in lignin-xylan |
8 | 1425 | Asymmetric C–H deformation in lignin-cellulose |
9 | 1375 | C–H deformation in cellulose and hemicellulose |
10 | 1313 | Syringyl ring breathing in lignin |
11 | 1263 | Guaiacyl ring breathing, C–O stretch in lignin |
12 | 1244 | Syringyl ring and C–O stretch in lignin and xylan |
13 | 1230 | C–O stretching in hemicellulose |
14 | 1154 | C–O–C vibration in the pyranose ring of the cellulose and stretching C = O in the aliphatic groups of the hemicellulose |
15 | 1048 | C–O stretch in cellulose and hemicellulose |
16 | 1024 | C–O, C–C and C–H stretching of alcohol, pyranoses ring from glucose |
17 | 896 | C–H deformation in cellulose |