These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Dependence of optical properties of oligo-para-phenylenes on torsional modes and chain length.
    Author: Lukes V, Aquino AJ, Lischka H, Kauffmann HF.
    Journal: J Phys Chem B; 2007 Jul 19; 111(28):7954-62. PubMed ID: 17592865.
    Abstract:
    A systematic characterization of excited-state properties of para-phenylene oligomers constructed from two to eight aromatic rings is presented using density functional theory (DFT) and the coupled-cluster singles and doubles (CC2) method. Geometry optimizations have been performed for the ground state and for the electronically excited state. Vertical excitations and the fluorescence transitions have been calculated. Time-dependent DFT (TDDFT) method underestimates excitation and fluorescence energies systematically in comparison with experimental results. The computed TDDFT lifetime for the polymer limit (0.43 ns) is in agreement with the experimental value of 0.55 ns. The TDDFT torsional potential curves were investigated for biphenyl, terphenyl, and quarterphenyl oligomers in their electronic ground and excited states. Our calculations show an increase in the separation of the lowest excited state (S1) to the next higher one with increasing molecular size. No indication is found for state crossings of the S1 state with higher ones from planar structures up to torsional angles of 60 degrees to 70 degrees. Thus, an adiabatic description of the dynamics of the S1 state might significantly simplify any dynamics simulations of torsional broadenings.
    [Abstract] [Full Text] [Related] [New Search]