Ultrafast dynamics of gas-phase excited-state intramolecular proton transfer in 1-hydroxy-2-acetonaphthone

The excited-state dynamics of 1-hydroxy-2-acetonaphthone (HAN) was studied in the gas phase using femtosecond time-resolved multiphoton ionization spe ctroscopy. Following femtosecond excitation to its S-1 state, HAN was found to exhibit a biexponential decay behavior which can be consistently interp reted in terms of rapid excited-state intramolecular proton transfer (ESIPT ) followed by other slower decay channels. The results revealed that ESIPT in HAN (S-1) occurs in similar to 60-85 ps in the energy range studied and suggested the existence of an energy barrier to tautomerization. (C) 1999 E lsevier Science B.V. All rights reserved.