Ondarse-Alvarez, Dianelys and Nelson, Tammie and Lupton, John M. and Tretiak, Sergei and Fernandez-Alberti, Sebastian (2018) Let Digons be Bygones: The Fate of Excitons in Curved pi-Systems. JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 9 (24). 7123-+. ISSN 1948-7185,
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We explore the diverse origins of unpolarized absorption and emission of molecular polygons consisting of pi-conjugated oligomer chains held in a bent geometry by strain controlled at the vertex units. For this purpose, we make use of atomistic nonadiabatic excited-state molecular dynamics simulations of a bichromophore molecular polygon (digon) with bent chromophore chains. Both structural and photoexcited dynamics were found to affect polarization features. Bending strain induces exciton localization on individual chromophore units of the conjugated chains. The latter display different transition dipole moment orientations, a feature not present in the linear oligomer counterparts. In addition, bending makes exciton localization very sensitive to molecular distortions induced by thermal fluctuations. The excited-state dynamics reveals an ultrafast intramolecular energy redistribution that spreads the exciton equally among spatially separated chromophore fragments within the molecular system. As a result, digons become virtually unpolarized absorbers and emitters, in agreement with recent experimental studies on the single-molecule level.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ENERGY-TRANSFER; ELECTRONIC EXCITATIONS; CONJUGATED POLYMERS; MOLECULAR-DYNAMICS; PHOTOPHYSICS; LOCALIZATION; POLARIZATION; RELAXATION; MODELS; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group John Lupton |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 04 Oct 2019 05:44 |
| Last Modified: | 07 Oct 2019 05:59 |
| URI: | https://pred.uni-regensburg.de/id/eprint/13341 |
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