Journal of Chemical Physics 2005-12-15

Mega three-photon absorption cross-section enhancement in pseudoisocyanine J-aggregates.

Ion Cohanoschi, Amel Barbot, Kevin D Belfield, Sheng Yao, Florencio E Hernandez

Index: J. Chem. Phys. 123(23) , 231104, (2005)

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Abstract

Herein we report an extraordinary three-photon absorption cross-section (sigma'3) enhancement in J-aggregates supramolecular systems. The much higher value of sigma'3 in PIC J-aggregate (2.5 x 10(-71) cm6 s2 ph(-2)) compared to typical values obtained in organic molecules (10(-80) cm6 s2 ph(-2)) is attributed to the strong molecular transition dipole moment coupling in the supramolecular assembly. Three-photon absorption of PIC J-aggregates and monomer aqueous solutions were measured using the well known open aperture Z-scan technique pumping with a 25 ps pulse laser-OPG system at 1720 nm. This novel result opens new expectations for applications of supramolecular systems in bioimaging and medicine.