Anomalous Linear Dichroism in Bent Chromophores of π-conjugated Polymers: Departure from the Franck-Condon Principle.
Phys Rev Lett
; 122(5): 057402, 2019 Feb 08.
Article
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| MEDLINE
| ID: mdl-30821996
We examine the influence of bending of π-conjugated chromophores on photoluminescence (PL) by spectrally resolving the depolarization of fluorescence on the single-molecule level. The effect of excited-state mixing mediated by molecular vibrations is manifested in the departure from the usual achromatic linear dichroism of fluorescence, with the polarization anisotropy decreasing in the vibronic progression. Bent chromophores reveal an overall increase in vibronic PL intensity with polarization orthogonal to the molecular long axis. This manifestation of the Renner-Herzberg-Teller (RHT) effect illustrates the breakdown of the Franck-Condon principle in macromolecules used in organic electronics, providing information on the orientation of transition-dipole moments and the origin of spectral broadening. While some of the spectral signatures of the RHT effect appear similar to those of H aggregation in molecular dimers, discrimination between the two phenomena is straightforward since H aggregation does not induce anomalous linear dichroism.
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01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Phys Rev Lett
Año:
2019
Tipo del documento:
Article
País de afiliación:
Alemania
Pais de publicación:
Estados Unidos