Wilhelm, P. and Vogelsang, J. and Schoenfelder, N. and Hoeger, S. and Lupton, J. M. (2019) Anomalous Linear Dichroism in Bent Chromophores of pi-conjugated Polymers: Departure from the Franck-Condon Principle. PHYSICAL REVIEW LETTERS, 122 (5): 057402. ISSN 0031-9007, 1079-7114
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We examine the influence of bending of pi-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.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | SPECTROSCOPY; FLUORESCENCE; ELECTRON; SYSTEMS; FILM; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group John Lupton |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 17 Apr 2020 11:35 |
| Last Modified: | 17 Apr 2020 11:35 |
| URI: | https://pred.uni-regensburg.de/id/eprint/27559 |
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