Excited state relaxation in cationic pentamethine cyanines studied by time-resolved spectroscopy

In this work, we examined the nature and pathways of electronic excitation relaxation at low temperature in cationic pentamethine pyrylocyanine dye, which ground state is characterized by symmetric non-symmetric localization charge on carbon chain between terminal groups. The such localizations close to polymethine polyene conformations, respectively. effect symmetry breaking during two-way transition – optically excited properties dyes considered. Combined quantum-chemical calculations time-resolved spectral measurements allowed us characterize structures states with specific peaks transitions lifetimes. features structure dye are attributed large-radius polaron formation, whereas for model excitons formed double bonds can be used analyze pathways. energy diagram has been proposed. proposed characteristic cyanine distribution groups states. • Pathways studied. Symmetric possible. Quantum-chemical were used. Polymethine formation. exciton applied dye.