| Wavenumber (cm−1) | Assignment |
|---|---|
| 3332 | U1, U2, ICU / N-H stretching |
| 2926 | C-H stretching |
| 2270 | N=C=O asymmetric stretching |
| 1710 | U1, ICU / C=O stretching |
| 1654 | U2 (Urea) / C=O stretching |
| 1598 | U1, U2, ICU / Phenyl Ring stretching |
| 1510 | U1, U2 / N-H bending |
| 1411 | Isocyanurate ring / C-N stretching |
| 1221 | Urethane / C-N & C-O stretching |