Cooperative Enhancement of Two-Photon Absorption in Self-Assembled Zinc-Porphyrin Nanostructures

作者：Mikhaylov Alexander; Kondratuk Dmitry V; Cnossen Arjen; Anderson Harry L^*; Drobizhev Mikhail; Rebane Aleksander^*

来源：Journal of Physical Chemistry C, 2016, 120(21): 11663-11670.

DOI：10.1021/acs.jpcc.6b01394

Femtosecond two-photon absorption (2PA) spectra were measured of a series of butadiyne-linked zinc-porphyrin oligomers assembled in single- and double-strand linear and cyclic structures containing 6, 12, or 24 porphyrin units, in the excitation wavelength range 900-1600 nm. We observe strong enhancement of the 2PA cross-section in the Soret region, with maximum values up to sigma(2pA) similar to 10(5) GM depending on the geometry of the construct, which we quantitatively explain in terms of a three essential energy level model and cooperative enhancement of the transition dipole moments between the states. The Zn-coordinated template-bound ring of 6 porphyrin units, which resembles some natural light-harvesting systems, results in thee highest 2PA cross-section per porphyrin unit (similar to 10(4) GM). It is remarkable that this molecule gives such strong sigma(2pA), when the S-0-S-1 (0-0) transition is essentially forbidden for one photon transition.

• 出版日期2016-6-2