Abstract:
The spectral and kinetic properties of photoluminescence of mixed Langmuir–Blodgett (LB) films
of eosin decyl ether and palmitic acid on a solid substrate are studied. The electronic absorption and fluorescence
spectra of the films are identical to the spectra of the dye in ethanol. An increase in the dye concentration
in a monolayer results in the appearance of a dimer absorption band, quenching of fluorescence of monomers,
and the red shift of the spectral bands. At 90 K, the distinct phosphorescence and delayed fluorescence bands
of LB films were observed. The decay kinetics of phosphorescence and delayed fluorescence is nonexponential.
It is shown that the decay curve of delayed fluorescence is determined by triplet–triplet annihilation (TTA) and
T1S1 triplet–singlet intersystem crossing (IS). The initial nonexponential phosphorescence decay is
caused the dominant contribution of TTA to the decay of triplet molecules. The experimental data are interpreted
based on the mechanisms of exchange–resonance and inductive–resonance annihilation.
