The assignments of main absorption bands of KL and the fractions^a.

Band (cm−1)	Assignments
834	C–H out of plane in G
1031	Aromatic C–H in the plane deformation of G and S
1116	S rings breathing
1164	H rings breathing
1218	C–O stretch vibration
1268	G ring breathing
1329	S skeleton vibration, C–C and C–O stretch vibration
1425	C–H deformation in lignin
1461	Aromatic ring vibration
1514	Aromatic squel vibration
1608	Aromatic squel vibration
1700	C O stretching in unconjugated or carboxyl groups

^aS: syringyl; G: guaiacyl.