Table 1 Assignments of the main silica bands in the 700- to 4,000 cm −1 region
Band maximum (KBr powder, cm−1) | Assignmenta | Reference |
---|---|---|
3,745 | ν (isolated silanol groups) Si-OH | |
3,700 to 3,000 | ν hydrogen-bonded silanols (overlapping of the stretching modes in hydrogen-bonded hydroxyl bands produced by O-H bonds in adsorbed water and Si-OH) | |
1,867 and 1,980 | Si-O-Si stretching modes | |
Approximately 1,628 to 1,630 | Proton-containing components σOH (silanol groups and the deformation vibrations of the O-H groups in physically adsorbed molecular water at the silica surface) | |
Approximately 1,083 | Si-O-Si stretching | |
1,000 to 1,300 | νas, anti-symmetric stretching of Si-O-Si bonds | [38] |
932 to 939 | Si-OH stretching | |
Approximately 809 | Bending vibration of Si-O-Si bonds | |
Approximately 790 | Bending modes in Si-OH bonds |