Time-resolved infrared study of the relaxation process of the intramolecular excited-state proton transfer in 2-naphthyl-3-hydroxychromone

Sub-microsecond time-resolved infrared spectroscopy has been used to investigate the ground-state relaxation process following the excited-state proton transfer in 2-(2′-naphthyl)-3-hydroxychromone in chloroform. Two transient species with decay times of 5.3 μs (1270 and 1230–1260 cm−1) and 500–600 μs (1220–1240 cm−1) were observed. These transient species seem to be attributable to ground-state tautomers. This observation is consistent with those by transient absorption and two-step laser-induced fluorescence.