Novel insights on the vibronic transitions in free base <i>meso</i>-tetrapyridyl porphyrin

ORAL

Abstract

We present novel results on the free base 5,10,15,20-meso-tetra(pyridyl)-21H,23H-porphyrin (H2TPyP). This molecule presents complex electronic and vibrational properties and in spite of the vast literature reporting the transitions observed in its absorption and fluorescence spectra, a more accurate interpretation has been kept elusive. In particular, we show that the molecule’s Q-band is clearly developed into many electronic and vibronic transitions, whose the well-known “four orbital model” finds it difficult to reconcile. Using distinct spectroscopy techniques, we conclude that both Qx- and Qy-bands comprise, in fact, two quasi-degenerated electronic states together with their respective vibronic progressions each. The analysis of the Huang-Rhys factors and complementary time- and polarization-resolved measurements reinforce the need for the proposed Q-band multi features remodeling.

*The authors are grateful to the Professors Waldeci Paraguassu and Sanclayton Moreira, from the Graduate Program in Physics of the Federal University of Para and Prof. Gerard J. Meyer from Department of Chemistry of The University of North Carolina at Chapel Hill, for granting the access to their experimental facilities.

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Presenters

  • Keshav Sharma

    • Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama, United States
    • University of Alabama

Authors

  • Jefferson Marcio Sanches Lopes

    • Graduate Program in Physics, Federal University of Para, Belem, PA, Brazil
    • Federal University of Pará

  • Keshav Sharma

    • Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama, United States
    • University of Alabama

  • Renato Neiva Sampaio

    • Department of Chemistry, The University of North Carolina at Chapel Hill, Murray Hall, Chapel Hill, NC, United States
    • University of North Carolina at Chapel Hill

  • Alzir Azevedo Batista

    • Department of Chemistry, Federal University of Sao Carlos, Sao Carlos, SP, Brazil
    • Federal University of São Carlos

  • Amando Siuiti Ito

    • College of Philosophy, Sciences, and Letters of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil.
    • University of São Paulo

  • Antonio Eduardo da Hora Machado

    • Institute of Chemistry, Federal University of Uberlandia, Uberlandia, MG, Brazil.

  • Paulo T Araujo

    • Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama, United States
    • University of Alabama
    • Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, Alabama 35487, USA

  • Newton M Barbosa Neto

    • Graduate Program in Physics, Federal University of Para, Belem, PA, Brazil
    • Federal University of Pará
    • Instituto de Ciências Exatas e Naturais – Programa de Pós-graduação em Física, Universidade Federal do Pará, Belém PA 66075-110, Brazil