Effective conjugation and Raman intensities in oligo(para-phenylene)s: A microscopic view from first-principles calculations

Georg Heimel, Dieter Somitsch, Peter Knoll, Jean Luc Bŕdas, Egbert Zojer

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Electron-phonon coupling in oligo(para-phenylene)s is addressed in terms of the off-resonance Raman intensities of two distinct modes at 1220 and 1280 cm-1. On the basis of Albrecht's theory, vibrational coupling and Raman intensities are calculated from first-principles quantum-chemical methods. A few-state model is used to evaluate the dependence of the mode intensities on oligomer length, planarity, and excitation wavelength. The link between electron delocalizationconjugation and Raman intensities is highlighted. Extending on prior studies, the present work focuses on providing an in-depth understanding of the origin of this correlation in addition to reproducing experimental findings. The model applied here allows us to interpret the results on a microscopic, quantum-mechanical basis and to relate the observed trends to the molecular orbital structure and nature of the excited states in this class of materials. We find quantitative agreement between the results of the calculations and those of measurements performed on oligo(para-phenylene)s of various chain lengths in the solid state and in solution.

Original languageEnglish (US)
Article number114511
JournalJournal of Chemical Physics
Volume122
Issue number11
DOIs
StatePublished - Mar 15 2005
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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