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Proceedings Paper

Phonon spectroscopy in pi-conjugated polymers: the role of the excited electronic states
Author(s): Eitan A. Ehrenfreund; Z. Valy Vardeny
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Paper Abstract

The Raman active vibrational modes in (pi) -conjugated polymers are known to have different frequencies in different types of experiments. The best known examples are the resonant Raman scattering (RRS) and doping or photoinduced absorption infrared active vibrations (IRAV) measurements, in which the same modes appear at different energies. Other examples are the phonon side bands, accompanying the polarons, bipolarons, and solitons absorption bands, in which the same modes give rise to different side band energies. In this work we discuss RRS and IRAV measurements and correlate their experimentally observed frequencies with the relevant electronic state that is active in this type of experiment. We show that the IRAV frequencies are lower than those of RRS since the relevant energy levels of charged solitons and/or polarons are closer to the ground state than the optically allowed 1Bu state of the neutral polymer. Thus a new insight into the meaning of the `pinning' potential, which is associated with the lowest frequency IRAV mode is obtained.

Paper Details

Date Published: 1 December 1997
PDF: 9 pages
Proc. SPIE 3145, Optical Probes of Conjugated Polymers, (1 December 1997); doi: 10.1117/12.295532
Show Author Affiliations
Eitan A. Ehrenfreund, Technion-Israel Institute of Technology (Israel)
Z. Valy Vardeny, Univ. of Utah (United States)

Published in SPIE Proceedings Vol. 3145:
Optical Probes of Conjugated Polymers
Z. Valy Vardeny; Lewis J. Rothberg, Editor(s)

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