Photo-induced reorganization of molecular packing of amphi-PIC J-aggregates (single J-aggregate spectroscopy)

Confocal luminescence microscopy has been used to excite and collect luminescence from single amphi-PIC J-aggregate. Two types of J-aggregates have been revealed in the luminescence image: bead-like J-aggregates, which diameter is less than I pm and rod-like ones, which length is about 3 pm and diameter is less than I pm. It has been found that single rod-like and bead-like J-aggregates exhibit different luminescence bands with different decay parameters. At the off-resonance blue tail excitation, the J-aggregate exciton luminescence disappeared within a certain time period and a new band appeared, which cannot be attributed to the monomer emission. The luminescence image shows that the J-aggregate is not destroyed. However, J-aggregate storage in darkness does not recover its exciton luminescence. (c) 2004 Elsevier B.V. All rights reserved.