Table 2.
Lifetimes, preexponential factors, and average lifetimes as a function of pH for transient species formed upon Trp excitation
| Wavelength/species | Molecule | pH | Mean lifetime | Lifetimes and preexponential factors for global fitting |
R2 | ||
|---|---|---|---|---|---|---|---|
| τ1 (μs) | τ2 (μs) | ||||||
| 330 nm (0–50 μs data set) | Tryptophan | 1.89 ± 0.06 | 25.1 ± 1.00 | 0.99133 | |||
| Trp· | 〈τ〉 (μs] | α1 | α2 | ||||
| 4.0 | 24.8 | 0.13 ± 0.02 | 0.87 ± 0.01 | ||||
| 7.5 | 23.9 | 0.41 ± 0.01 | 0.59 ± 0.01 | ||||
| 8.5 | 24.0 | 0.40 ± 0.01 | 0.60 ± 0.01 | ||||
| 10.0 | 23.2 | 0.54 ± 0.01 | 0.46 ± 0.01 | ||||
| τ1 (μs) | τ2 (μs) | ||||||
| 550 nm (0–50 μs data set) | Tryptophan | 0.34 ± 0.01 | 2.35 ± 0.03 | 0.98266 | |||
| Trp·+ | 〈τ〉 (μs) | α1 | α2 | ||||
| 4.0 | 34.2 | 0.97 ± 0.03 | 0.03 ± 0.02 | ||||
| 7.5 | 32.5 | 0.94 ± 0.01 | 0.06 ± 0.01 | ||||
| 8.5 | 30.1 | 0.87 ± 0.02 | 0.13 ± 0.01 | ||||
| 10.0 | 20.4 | 0.56 ± 0.01 | 0.44 ± 0.01 | ||||
| τ1 (μs) | τ2 (μs) | τ3 (μs) | |||||
| 330 nm (0–1 ms data set) | Tryptophan | 3.02 ± 0.08 | 40.1 ± 0.2 | 316 ± 11 | 0.99709 | ||
| Trp· | 〈τ〉 (μs) | α1 | α2 | α3 | |||
| 8.5 | 292 | 0.45 ± 0.01 | 0.22 ± 0.01 | 0.33 ± 0.01 | |||
| 10.0 | 294 | 0.45 ± 0.01 | 0.20 ± 0.01 | 0.35 ± 0.01 | |||
| τ1 (μs) | τ2 (μs) | τ3 (μs) | |||||
| 520 nm (0–1 ms data set) | Tryptophan | 3.13 ± 0.03 | 33.6 ± 2.1 | 291 ± 16 | 0.99702 | ||
| Trp· | 〈τ〉 (μs) | α1 | α2 | α3 | |||
| 8.5 | 260 | 0.71 ± 0.01 | 0.12 ± 0.01 | 0.17 ± 0.01 | |||
| 10.0 | 249 | 0.80 ± 0.01 | 0.09 ± 0.00 | 0.11 ± 0.00 | |||
| τ1 (μs) | τ2 (μs) | ||||||
| 560 nm (0–1 ms data set) | Tryptophan | 2,87 ± 0.02 | 100 ± 4.3 | 0.99701 | |||
| Trp·+ | 〈τ〉 (μs) | α1 | α2 | ||||
| 7.5 | 82.3 | 0.11 ± 0.00 | 0.89 ± 0.01 | ||||
| 8.5 | 78.0 | 0.09 ± 0.00 | 0.91 ± 0.01 | ||||
| 10.0 | 74.8 | 0.08 ± 0.00 | 0.92 ± 0.01 | ||||
| τ1 (μs) | τ2 (μs) | ||||||
| 450 nm (0–50 μs data set) | Tryptophan | 1.51 ± 0.03 | 12.4 ± 0.4 0.99137 | ||||
| 3Trp | 〈τ〉 (μs) | α1 | α2 | ||||
| 4.0 | 11.8 | 0.33 ± 0.01 | 0.67 ± 0.01 | ||||
| 7.5 | 10.6 | 0.62 ± 0.01 | 0.38 ± 0.01 | ||||
| 8.5 | 11.2 | 0.51 ± 0.01 | 0.49 ± 0.01 | ||||
| 10.0 | 10.9 | 0.57 ± 0.01 | 0.43 ± 0.01 | ||||