Ultrafast electronic energy relaxation in a conjugated dendrimer leading to inter-branch energy redistribution
| Autor: | Sergei Tretiak, Sebastian Fernandez-Alberti, Sevnur Kömürlü, Valeria D. Kleiman, D. Ondarse-Alvarez, Gustavo Pierdominici-Sottile, Adrian E. Roitberg |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Exciton
General Physics and Astronomy NA-ESMD 010402 general chemistry Molecular Dynamics 01 natural sciences dendrimers purl.org/becyt/ford/1 [https] Delocalized electron Dendrimer 0103 physical sciences purl.org/becyt/ford/1.4 [https] Physical and Theoretical Chemistry Spectroscopy 010304 chemical physics Chemistry Otras Ciencias Químicas Ciencias Químicas Chromophore 0104 chemical sciences Photoexcitation Excited state Atomic physics AMBER Excitation CIENCIAS NATURALES Y EXACTAS |
| Zdroj: | CONICET Digital (CONICET) Consejo Nacional de Investigaciones Científicas y Técnicas instacron:CONICET |
| Popis: | Dendrimers are arrays of coupled chromophores, where the energy of each unit depends on its structure and conformation. The light harvesting and energy funneling properties are strongly dependent on their highly branched conjugated architecture. Herein, the photoexcitation and subsequent ultrafast electronic energy relaxation and redistribution of a first generation dendrimer (1) are analyzed combining theoretical and experimental studies. Dendrimer 1 consists of three linear phenylene-ethynylene (PE) units, or branches, attached in the meta position to a central group opening up the possibility of inter-branch energy transfer. Excited state dynamics are explored using both time-resolved spectroscopy and non-adiabatic excited state molecular dynamics simulations. Our results indicate a subpicosecond loss of anisotropy due to an initial excitation into several states with different spatial localizations, followed by exciton self-trapping on different units. This exciton hops between branches. The absence of an energy gradient leads to an ultrafast energy redistribution among isoenergetic chromophore units. At long times we observe similar probabilities for each branch to retain significant contributions of the transition density of the lowest electronic excited-state. The observed unpolarized emission is attributed to the contraction of the electronic wavefunction onto a single branch with frequent interbranch hops, and not to its delocalization over the whole dendrimer. Fil: Ondarse Alvarez, Dianelys. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina Fil: Kömürlü, S.. University of Florida; Estados Unidos Fil: Roitberg, Adrián. University of Florida; Estados Unidos Fil: Pierdominici Sottile, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina Fil: Tretiak, S.. Los Alamos National Laboratory; Estados Unidos Fil: Fernández Alberti, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina Fil: Kleiman, V. D.. University of Florida; Estados Unidos |
| Databáze: | OpenAIRE |
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