Photophysics of aggregated 9-methylthiacarbocyanine bound to polyanions

The photophysical properties of 3,3 ′-diethyl-9-methylthiacarbocyanine (DTC) were studied in the presence of polystyrene sulfonate (PSS), polyacrylic acid (PAA) and polymethacrylic acid (PMA). The absorption spectra reflect a monomer/dimer equilibrium in neat aqueous solution and a shift towards bou...

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Bibliographic Details
Published in:Chemical physics letters 2002-05, Vol.357 (5), p.434-439
Main Authors: Chibisov, Alexander K., Görner, Helmut
Format: Article
Language:English
Subjects:
Atomic and molecular physics
Exact sciences and technology
Fluorescence and phosphorescence spectra
Fluorescence and phosphorescence
radiationless transitions, quenching (intersystem crossing, internal conversion)
Molecular properties and interactions with photons
Molecular spectra
Physics
Visible spectra
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Summary:The photophysical properties of 3,3 ′-diethyl-9-methylthiacarbocyanine (DTC) were studied in the presence of polystyrene sulfonate (PSS), polyacrylic acid (PAA) and polymethacrylic acid (PMA). The absorption spectra reflect a monomer/dimer equilibrium in neat aqueous solution and a shift towards bound H-aggregates, bound dimers and bound monomers on increasing the ratio of polyanion residue to dye concentrations ( r). These equilibria also determine the photodeactivation modes of DTC. The fluorescence intensity is reduced, when dimers and aggregates are present and strongly enhanced for low dye loading ( r=10 4). In contrast, the quantum yield of intersystem crossing is enhanced for bound dimers ( r=10 3).
ISSN:0009-2614
1873-4448
DOI:10.1016/S0009-2614(02)00531-6