Table 2.
Summary of Raman bands assignments
| Deacetylated corn stover | Xylan models | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Control | After 55% xylan removal | Assignment | Species | Oat spelts xylan | Birchwood xylan | Xylo oligo DP2-7 | Assignment | d-Xylose | Assignment in d-xylose |
| 320w | 320w | δ(CCC) ring | Cellulose | 320w | 320w | 320m | |||
| 330vw | OH bend coupled with CO def | ||||||||
| 355w | 355w | δ(CCC) ring | Cellulose | 355w | 355w | 355sh | – | ||
| 380sh | 380w | δ(CCC) ring | Cellulose | – | – | – | – | ||
| 407s | Ring bend coupled with OH bend | ||||||||
| 424m | 424m | δ(CCC) and δ(CCO) ring | Cellulose, xylan | 424m | 424m | 415s | Xylan δ(CCC) and δ(CCO) ring | 433s | CO deformation |
| 492m | 492m | Glycosidic ν(CCC) | Cellulose, xylan | 492m | 492m | 492m | Xylan glycosidic ν(CCC) | – | |
| 530sh | 530sh | 530sh | 530s | 530s | CO deformation couple with ring bend | ||||
| 563m | 563m | δ(COC) ring | Cellulose, xylan | 563m | 563s | 570sh | Xylan δ(COC) ring | 567m | CO def coupled with methine def |
| 613m | CO def coupled with CO ring bend | ||||||||
| 678s | 678sh | Pyranoid rings | 678sh | 678m | – | – | |||
| 770s | 770m | Xyloglucan, possibly some lignin ring and side chains | Xyloglucan lignin, ferulic acid | 770m | 770s | – | Glucuronic acid remainings | 760s | CO ring str and bend coupled with CC ring str and CO str and bend |
| 820–860s | 820–860s | Glycosidic bonds and backbone vibration in hexose | 820-860s | 820-860s | – | – | |||
| 920m | 920sh | COC str coupled with CC ring str. | Xylan | 920sh | 920sh | 900s | Xylan COC str coupled with CC ring str | 907vs | Symmetric COC str coupled with CC ring str |
| 930m | CO and CC stretch coupled with methine deformation | ||||||||
| 1007s | 1007w | ν(C–C) and ν(C–OH) | Xylan | 1007w | 1007m | 990m | Xylan ν(C–C) and ν(C–OH) | 1019m | CC and CO ring str coupled with methine deformation |
| 1095m | 1095m | COC stretch symmetric | Cellulose | 1095sh | 1095sh | 1095sh | 1089s | CO str coupled with CC str and methine def | |
| 1123s | 1123s | ν (COC), glycosidic; ring breathing, symmetric | Cellulose | 1123m | 1123m | 1123m | 1111s | CO str coupled with CC ring str | |
| 1219s | 1219w | C-O str, δ(CH) and/or δ(COH) | Xylan | 1219m | 1219s | 1250w | C–O str, δ(CH) and/or δ(COH) | 1240m | Methine def coupled with OH i.p. bend |
| 1313s | 1313m | Cellulose aliphatic O–H bend vibration, xylan C3-OH | Cellulose, xylan | 1313m | 1313s | 1315m | 1313m | Anomeric methine def coupled with methine def | |
| 1340m | Methine def coupled with methylene wag | ||||||||
| 1383m | 1383m | Cellulose δ(CH2), δ(HCC), δ(HCO) and δ(COH), lignin phenolic O–H, xylan δ(CH) and δ(OH) | Cellulose, lignin, xylan | 1383m | 1383m | 1383s | Xylan δ(CH) and δ(OH) | 1383m | Methylene wag coupled with OH i.p. bend and methine def |
| 1395m | OH i.p. bend coupled methylene wag and methine def | ||||||||
| 1471s | 1471w | Xylan OH and CH2 | Xylan | 1471w | 1471m | 1471s | Xylan OH and CH2 | 1471m | Methylene scissors coupled with wag |
| 1604s | 1604s | Lignin aromatic ring | Lignin | – | – | 1604m | Residual lignin aromatic ring and coniferaldehyde | – | |
| 1634s | 1634s | C=C stretch in coniferaldehyde lignin | Lignin | – | – | 1634m | – | ||
Conventional symbolism indicating relative intensity
vw very weak, w weak, m medium, s strong, vs very strong, sh shoulder