EXCITED-STATES AND REDUCED AND OXIDIZED FORMS OF A TEXTILE DIAZO DYE,NAPHTHOL BLUE BLACK, SPECTRAL CHARACTERIZATION USING LASER FLASH-PHOTOLYSIS AND PULSE-RADIOLYSIS STUDIES

The excited singlet and triplet states of a diazo textile dye (Naphtho l Blue Black) have been investigated by pico and nanosecond flash phot olysis. The excited singlet state shows a difference absorption maximu m at 500 nm and has a lifetime of 25-30 ps in ethanol. The triplet exc ited state generated by triplet-triplet energy transfer shows an absor ption maxima at 710-730 nm. The oxidized form as well as the reduced f orm of the diazo dye have been generated pulse radiolytically by react ing with azide and e(aq) radicals, respectively. Preliminary results o f the photoelectrochemical irreversible reduction of Naphthol Blue Bla ck in colloidal TiO2 are also reported. Copyright (C) 1997 Elsevier Sc ience Ltd.