Table 2.
Assignments of FTIR absorption bands. Adapted from Faix.
| Number in Figure 8 | Band (cm−1) | Assignment |
|---|---|---|
| 1 | 3302 | O–H Stretch |
| 2 | 2926 | C–H Stretch in methyl and methylene groups |
| 3 | 2852 | C–H Stretch in methyl and methylene groups |
| 4 | 1706 | C=O stretching |
| 5 | 1654 | C=O Stretch; in conjugated p-subst. aryl ketones |
| 6 | 1603 | aromatic skeletal vibrations plus C=O Stretch |
| 7 | 1513 | Aromatic skeletal vibrations |
| 8 | 1457 | Asymmetric bending deformation of methyl and methylene groups |
| 9 | 1424 | aromatic skeletal vibrations combined with C–H in-plane deform |
| 10 | 1355 | aliphatic C-H stretch in CH3 |
| 11 | 1331 | S ring and G ring condensed |
| 12 | 1262 | C–O of guaiacyl ring and C=O stretch |
| 13 | 1220 | C–C plus C–O stretch |
| 14 | 1160 | Typical for HGS lignin, conjugated C=O in ester groups |
| 15 | 1122 | aromatic C–H in-plane deformation (typical for S units), plus secondary alcohols, plus C=O stretch |
| 16 | 1031 | Aromatic C–H in-plane deformation, G > S; plus C–O deform, in primary alcohols; plus C=O Stretch (unconjugated) |
| 17 | 919 | C–H out-of-plane; aromatic |
| 18 | 836 | C–H out-of-plane in position 2 and 6 of S, and in all position of H units |