J-aggregates of tiacarbocyanine derivative are investigated in frozen solution at low temperatures by optical spectroscopy and spectral hole burning. It is found that absorption and luminescence bands have inhomogeneous widths of 220 and 130 cm-1 at 5 K respectively used in contrast to pseudoisocyanine (PIC) J-bands are separated by Stokes shift of 100 cm-1. Moreover, J-aggregate fluorescence spectrum depends drastically on the temperature and initial dye concentration. Temperature broadening of spectral hole, burnt in the J-absorption band differs qualitatively from that, burnt in the monomeric band. It differs also, but quantitatively, from broadening of the spectral hole in J-band of PIC. These observations are discussed in terms of nonradiative relaxation of excitons in the system under investigation.
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