Femtosecond dynamics of excited-state intramolecular proton transfer in o-tosylaminobenzaldehyde

Dynamics of excited-state intramolecular proton transfer (ESIPT) in o-tosylaminobenzaldehyde has been studied by femtosecond absorption spectroscopy with a time resolution of 30 fs. The characteristic time of this process is similar to 100 fs. Differential absorption rate curves exhibit oscillations that are consistent with theoretically predicted ESIPT-promoting vibrational modes. Efficient nonradiative deactivation with a rate constant of 6.25 x 10(10) s(-1) occurs in the excited product of proton transfer, with internal rotation followed by intersystem crossing being one of the feasible deactivation pathways.