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Proceedings Paper

Broad bandwidth near-IR two-photon absorption in conjugated porphyrin-core dendrimers
Author(s): Aleks Rebane; Nikolay Makarov; Mikhail Drobizhev; Charles W. Spangler; Aijun Gong; Fanqing Meng
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Paper Abstract

We study two-photon absorption (2PA) spectra and absolute 2PA cross sections, as well as fluorescence emission- and excitation spectra along with time resolved fluorescence in a series of new dendrimers, where a single porphyrin/phthalocyanine core is decorated with electron-donating/two-photon absorbing groups. We show that if the combined system has strong π-conjugation/multipolar charge transfer between the core and the attached group(s), then the observed 2PA undergoes cooperative enhancement, where the peak 2PA cross section reaches σ2=600-2000 GM in a broad transition wavelength region 375-500 nm (laser wavelengths 750-1000 nm). In the systems with less conjugation, the 2PA is less enhanced, and in the limit of very weak conjugation maximum σ2 remains essentially the sum of the cross sections of the constituents. We show that the conjugation strength correlates with the fluorescence emission properties. In particular, in the strongly linked systems the fluorescence originates mostly from the core porphyrin, whereas in the weakly linked systems the attached chromophores emit independently from the porphyrin. In intermediate conjugation strength case we observe non-exponential fluorescence decays and fluorescence rise times, which indicated Forster resonant energy transfer from the side groups to the core.

Paper Details

Date Published: 28 September 2007
PDF: 8 pages
Proc. SPIE 6653, Linear and Nonlinear Optics of Organic Materials VII, 665307 (28 September 2007); doi: 10.1117/12.734475
Show Author Affiliations
Aleks Rebane, Montana State Univ. (United States)
Nikolay Makarov, Montana State Univ. (United States)
Mikhail Drobizhev, Montana State Univ. (United States)
Charles W. Spangler, Montana State Univ. (United States)
Rasiris, Inc. (United States)
Aijun Gong, Rasiris, Inc. (United States)
Fanqing Meng, Rasiris, Inc. (United States)

Published in SPIE Proceedings Vol. 6653:
Linear and Nonlinear Optics of Organic Materials VII
Jean-Michel Nunzi, Editor(s)

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