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Proceedings Paper

Structure and excited state relaxation dynamics in nanoscale self-assembled arrays: multiporphyrin complexes, porphyrin-quantum dot composites
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Paper Abstract

Self-assembled nanoscale arrays of controllable geometry and composition (up to 8 tetrapyrroles) have been formed via non-covalent binding interactions of the meso-phenyl bridged Zn-octaethylporphyrin chemical dimers or trimers with di- /tetrapyridyl substituted porphyrin extra-ligands. In these complexes using steady-state and time-resolved (ps fluorescence and fs pump-probe) measurements pathways and efficiencies of the energy transfer photoinduced charge separation as well as exchange d-π effects have been studied in solutions of variable polarity at 77-293 K. The same principles of aggregation via the key-hole scheme "Zn-pyridyl" have been used also for the surface passivation of pyridylsubstituted tetrapyrroles on the coreshell semiconductor CdSe/ZnS quantum dots (QD) showing quantum confinement effects. Picosecond time-resolved and steady-state data reveal that CdSe/ZnS QD emission is multiexponential and the efficiency of its quenching by attached porphyrins (due to energy transfer and photoinduced charge separation) depends strongly on the number of anchoring groups their arrangement in the porphyrin molecule as well as on QD size and number of ZnS monolayers. The analysis of spectroscopic and kinetic findings reveals that on average only ~l/5 porphyrin molecules are assembled on the QD and a limited number of "vacancies" accessible for porphyrin attachment is available on the QD surface.

Paper Details

Date Published: 1 June 2005
PDF: 12 pages
Proc. SPIE 5849, Fifth Workshop on Atomic and Molecular Physics, (1 June 2005); doi: 10.1117/12.629399
Show Author Affiliations
E. I. Zenkevich, Institute of Molecular and Atomic Physics (Belarus)
C. von Borczyskowski, Univ. of Technology Chemnitz (Germany)

Published in SPIE Proceedings Vol. 5849:
Fifth Workshop on Atomic and Molecular Physics
Jerzy Kwela; Ryszard Drozdowski; Tomasz J. Wasowicz, Editor(s)

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