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The direct application of laser flash photolysis to cotton fabric dyed with a phthalocyanine dye
Author(s) -
Willsher Charles
Publication year - 1988
Publication title -
journal of the society of dyers and colourists
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 0037-9859
DOI - 10.1111/j.1478-4408.1988.tb01144.x
Subject(s) - flash photolysis , photochemistry , excited state , quenching (fluorescence) , phthalocyanine , chemistry , oxygen , fluorescence , dye laser , absorption (acoustics) , materials science , laser , optics , atomic physics , kinetics , organic chemistry , physics , quantum mechanics , reaction rate constant , composite material
Flash photolysis studies of sulphonated aluminium(III) phthalocyanine contained in cotton fabric show that the dye has essentially the same spectral behaviour as when dissolved in water, but the lifetime of excited states is longer. Following excitation of the Soret band, the triplet‐triplet absorption of the dye has a lifetime of 770±60 μ s in an oxygen‐free fabric, with inefficient quenching by oxygen observed only if the fibres are water‐saturated. S 1 S 0 fluorescence from the dye is detected only when the sample contains oxygen and the decay has two components; in the absence of oxygen T 2 T 1 emission occurs as well. Prolonged exposure to the 354nm exciting laser causes the build‐up of a red substance in the fabric, which is believed to be the product of one‐electron oxidation of the phthalocyanine. Electron acceptors and donors such as methyl viologen and hydroquinone have a limited quenching effect on the excited states of the dye. The observed behaviour of the dye is discussed in terms of the restricted diffusion of molecules within the cotton fibres and of the enhanced lifetimes of the excited states.