Table 1. Order of band changes during the PPTT process.
| Synchronous at Φ (ν1, ν2) | Asynchronous at ψ (ν1, ν2) | ν 1 a |
| (500, 750) cm–1 < 0 | (500, 750) cm–1 > 0 | Lag |
| (500, 1000) cm–1 < 0 | (500, 1000) cm–1 < 0 | Lead |
| (500, 1120) cm–1 > 0 | (500, 1120) cm–1 > 0 | Lead |
| (1000, 1120) cm–1 < 0 | (1000, 1120) cm–1 > 0 | Lag |
| (1000, 1586) cm–1 > 0 | (1000, 1586) cm–1 > 0 | Lead |
aThe term lead means that the intensity change of a band at ν1 occurs before ν2. The term lag means that the intensity change of a band at ν1 occurs after ν2.