2.

(a) Early time scale femtosecond TA data recorded for SAA in THF (λ_ex = 282 nm, excitation fluence = 235 μJ/cm², absorption ≈2.1 at the excitation wavelength), arrows guide spectral evolution. “DAS1” is the decay associated spectrum associated with the ESIPT process. (b) Late time scale femtosecond TA data recorded for SAA in THF (λ_ex = 280 nm, excitation fluence = 330 μJ/cm², absorption ≈0.31 at the excitation wavelength). (c) Kinetics monitored at indicated wavelengths from (a), together with global fits. (d) Kinetics monitored at indicated wavelengths from (b), together with global fits.