Femtosecond intramolecular proton transfer of vibrationally hot molecules in the electronic ground state

摘要: Abstract Intramolecular proton transfer and vibrational relaxation in 2-(2′-hydroxy-5′-methylphenyl)-benzotriazole are directly monitored spectrally temporally resolved experiments with femtosecond ultraviolet pulses. Within 500 fs after excitation of the original enol species, excited-state subsequent internal conversion create keto-type tautomers electronic ground state. The keto→enol back-transfer occurs a time constant 700±100 as is obvious from kinetics repopulation fast reaction produces vibrationally hot molecules strongly broadened S 0 →S 1 absorption spectrum. reshaping this band at later times gives evidence cooling within 30 ps.