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 + ν_3b

[30] [33] [40]

1154 (w)

Harmonic overtone or combination band

[33]

1087 (s)

Triply degenerated asymmetric stretching mode (ν_3a) of the P−O bond of the phosphate group

[31] [32]

1046 (s)

Triply degenerated asymmetric stretching mode (ν_3b) of the P−O bond of the phosphate group

[30]

1032 (sh)

Triply degenerated asymmetric stretching mode (ν_3c) 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 (ν_4a) of the O−P−O bonds of the phosphate group

[30] [31] [40]

574 (s, sh)

Triply degenerated bending mode (ν_4b) of the O−P−O bonds of the phosphate group

[30] [32] [40]

561 (s)

Triply degenerated bending mode (ν_4c) of the O−P−O bonds of the phosphate group

[30] [32] [40]

472 (w)

Double degenerated bending mode (ν_2a) of the O−P−O bonds of the phosphate group

[30] [32]

462 (w, sh)

Double degenerated bending mode (ν_2b) 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]