D.Frolov, S.Bagdonas, R.Rotomskis
Laser Research Centre, Vilnius University, Sauletekio 9, 2040 Vilnius Lithuania

• Introduction
• Materials and Methods
• Results and Discusion
• Conclusions
• References

The dynamics of energy relaxation under optical excitation in aqueous solutions of J-aggregates of TPPS₄ was investigated. Analysis of absorption difference spectra measured by means of picosecond absorption spectrometer with time resolution of 2 ps indicates that relaxation kinetics in excited J-aggregates of TPPS₄ can be described by the model of excitonic singlet-singlet annihilation in molecular structures. On the basis of diffusion restricted movement in the case of long range Förster dipole-dipole interaction the constant h was evaluated. The obtained value h=1/2 indicates that J-aggregates of TPPS₄ are of linear structure. Separate domain of such aggregate contains at least forty molecules. The exciton diffusion coefficient in such domain equals (4± 2) 10^-3M cm²s^-1 and exciton transition time - 1.75± 0.75 ps.

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