Peak (cm−1) | Assignment | Reference |
3572 (w) | Stretching mode, νs, of the hydroxyl group | [37] [38] [39] |
2070 (w) | Harmonic overtone or combination band | [33] |
2000 (w) | Harmonic overtone 2, ν3 or combination band ν1 + ν3b | [30] [33] [40] |
1154 (w) | Harmonic overtone or combination band | [33] |
1087 (s) | Triply degenerated asymmetric stretching mode (ν3a) of the P−O bond of the phosphate group | [31] [32] |
1046 (s) | Triply degenerated asymmetric stretching mode (ν3b) of the P−O bond of the phosphate group | [30] |
1032 (sh) | Triply degenerated asymmetric stretching mode (ν3c) of the P−O bond of the phosphate group | [30] [31] [40] |
962 (w) | Nondegenerated symmetric stretching mode (ν1) of the P−O bonds of the phosphate group | [30] [31] [32] [33] |
631 (m) | Librational mode (νL) of the hydroxyl group | [8] [29] |
602 (s, shp) | Triply degenerated bending mode (ν4a) of the O−P−O bonds of the phosphate group | [30] [31] [40] |
574 (s, sh) | Triply degenerated bending mode (ν4b) of the O−P−O bonds of the phosphate group | [30] [32] [40] |
561 (s) | Triply degenerated bending mode (ν4c) of the O−P−O bonds of the phosphate group | [30] [32] [40] |
472 (w) | Double degenerated bending mode (ν2a) of the O−P−O bonds of the phosphate group | [30] [32] |
462 (w, sh) | Double degenerated bending mode (ν2b) of the O−P−O bonds of the phosphate group | [30] [32] |
361 (w, sh) | HAP lattice vibration mode or combination band (ν1 − ν4) | [30] [33] |
355 (sh) | Translational mode (νT) of the hydroxyl group (ν3) | [30] |
342 (w, sh) | Translational mode (νT) of the hydroxyl group (ν3) | [8] [29] [30] |