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Titolo:
Franck-Condon spectra and electron-libration coupling in para-polyphenyls
Autore:
Karabunarliev, S; Bittner, ER; Baumgarten, M;
Indirizzi:
Univ Houston, Dept Chem, Houston, TX 77204 USA Univ Houston Houston TX USA 77204 uston, Dept Chem, Houston, TX 77204 USA Max Planck Inst Polymerforsch, D-55128 Mainz, Germany Max Planck Inst Polymerforsch Mainz Germany D-55128 55128 Mainz, Germany
Titolo Testata:
JOURNAL OF CHEMICAL PHYSICS
fascicolo: 13, volume: 114, anno: 2001,
pagine: 5863 - 5870
SICI:
0021-9606(20010401)114:13<5863:FSAECI>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
HEXAPHENYL POLYCRYSTALLINE FILMS; SITE-SELECTIVE FLUORESCENCE; OPTICAL-PROPERTIES; CONJUGATED OLIGOMERS; ELECTROABSORPTION SPECTROSCOPY; POLY(P-PHENYLENE VINYLENE); NEUTRON-DIFFRACTION; VIBRATIONAL-SPECTRA; ABSORPTION-SPECTRA; LADDER POLYMER;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
53
Recensione:
Indirizzi per estratti:
Indirizzo: Karabunarliev, S Univ Houston, Dept Chem, Univ Pk, Houston, TX 77204 USA Univ Houston Univ Pk Houston TX USA 77204 n, TX 77204 USA
Citazione:
S. Karabunarliev et al., "Franck-Condon spectra and electron-libration coupling in para-polyphenyls", J CHEM PHYS, 114(13), 2001, pp. 5863-5870

Abstract

Proceeding from quantum-chemical potential energy surfaces, we compute theabsorption and fluorescence spectra of conventional and ladder-type para-phenylene oligomers (OPP and OLPP) with up to 7 benzene rings. Electronically excited states are addressed by means of extended configuration interaction within a standard molecular all-valence-electron semiempirical Hamiltonian. Adiabatic excitation energies, interstate distortions and normal modes are used to compute Franck-Condon band shapes with rigorous consideration of vibrational structure. Theoretical spectra agree with the experiment and rationalize the striking disparities in the linear optical response of OPP and OLPP. Whereas electron-phonon coupling in OLPP is essentially restricted to the carbon-carbon bond-stretching modes, photoexcitation, and emissionprocesses in OPP are followed by significant relaxations in ring-torsionaldegrees of freedom. The broadening of spectra of OPP, especially pronounced in absorption, and the large Stokes shift between absorption and emissionare traced back to the strong coupling of electronic excitations and low-frequency libration motions. The results highlight the importance of ring-torsional flexibility in conjugated polymers. (C) 2001 American Institute of Physics.

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Documento generato il 01/12/20 alle ore 19:29:07