Zero-phonon transitions and vibronic coupling in the 1:1 charge-transfer crystal anthracene-pyromellitic-acid-dianhydride
✍ Scribed by D. Haarer
- Publisher
- Elsevier Science
- Year
- 1974
- Tongue
- English
- Weight
- 353 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
High resolution speclrn of the 1:l CT-crystal anthracene-pyromelljric-ni-id-di3nhydride (A.PLIDA) show nt low tcmperatures sharp structures in absorprion and in emission. We attribute these structures to a zero-phonon transition which is accompanied by vibronic satellites. The spectra yield the coupling strength of the CT-transition to the phonons and to the vibrational modes of both the donor and acceptor molecule. The optical spectra of organic 1: 1 charge-transfer (CT).crystals show several features which are characteristic of the electronic CT-transition. These features are: field of CT-spectroscopy. They enable us to examine CT-transition energies and vibronic frequencies in donor-acceptor crystals with an accuracy of a few wavenumbers. (i) broad and structureless absorption and emission bands with low temperature half widths of several hundred to more than a thousand wavenumbers [l-5] ;
(ii) a Franck-Condon gap between the absorption and emission peak which is of the order of a thousand wavenumbers;