ROLE OF TRIPLET-STATES IN THE REVERSE PROTON-TRANSFER MECHANISM OF 7-HYDROXY-1-INDANONE

The dynamics of the reverse proton transfer of 7-hydroxy-1-indanone have been investigated on the nanosecond time scale. The existence of a long-lived (> mu-s) species after excited-state intramolecular proton transfer is attributed to the tautomer triplet state. The observed tautomer emission by two-step laser-induced fluorescence (TSLIF) originates from T'2 --> T'n (prime denotes the tautomer species, n greater-than-or-equal-to 2) excitation followed by T'2 --> S'1 intersystem crossing (ISC). The yield of the T'2 --> S'1 ISC was measured to be 1.1 X 10(-3) in methylcyclohexane. A T-S ISC mechanism incorporating the fast rate of T'n-pi* - S'pi-pi* ISC is discussed.