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Ultrafast electronic energy relaxation in a conjugated dendrimer leading to inter-branch energy redistribution.
Ondarse-Alvarez, D; Kömürlü, S; Roitberg, A E; Pierdominici-Sottile, G; Tretiak, S; Fernandez-Alberti, S; Kleiman, V D.
Afiliação
  • Ondarse-Alvarez D; Departamento de Ciencia y Tecnologia, Universidad Nacional de Quilmes/CONICET, B1876BXD Bernal, Argentina. sfalberti@gmail.com.
  • Kömürlü S; Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA. kleiman@chem.ufl.edu.
  • Roitberg AE; Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA. kleiman@chem.ufl.edu.
  • Pierdominici-Sottile G; Departamento de Ciencia y Tecnologia, Universidad Nacional de Quilmes/CONICET, B1876BXD Bernal, Argentina. sfalberti@gmail.com.
  • Tretiak S; Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
  • Fernandez-Alberti S; Departamento de Ciencia y Tecnologia, Universidad Nacional de Quilmes/CONICET, B1876BXD Bernal, Argentina. sfalberti@gmail.com.
  • Kleiman VD; Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA. kleiman@chem.ufl.edu.
Phys Chem Chem Phys ; 18(36): 25080-25089, 2016 Sep 14.
Article em En | MEDLINE | ID: mdl-27711661
ABSTRACT
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.
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Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2016 Tipo de documento: Article
Buscar no Google
Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2016 Tipo de documento: Article