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Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory

Giovanelli, Luca and Lee, H.-L. and Lacaze-Dufaure, Corinne and Koudia, Mathieu and Clair, Sylvain and Lin, Y.-P. and Ksari, Younal and Themlin, Jean-Marc and Abel, Mathieu and Cafolla, Attilio A. Electronic structure of tetra(4-aminophenyl)porphyrin studied by photoemission, UV–Vis spectroscopy and density functional theory. (2017) Journal of Electron Spectroscopy and Related Phenomena, 218. 40-45. ISSN 0368-2048

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Official URL: http://dx.doi.org/10.1016/j.elspec.2017.05.005

Abstract

The valence and conduction bands of a thin film of tetra(4-aminophenyl)porphyrin (TAPP) are investi-gated by direct and inverse photoemission as well as by comparison to density functional theory (DFT)calculations. By projecting the electronic eigenfunctions onto the molecular framework it was possibleto interpret the origin of each spectroscopic feature. Although the majority of the photoemission spec-trum is attributed to the unsubstituted tetraphenylporphyrin (TPP) parent molecule, several featuresare clearly due to the amino substitution. Substitution also has important consequences for the energypositions of the frontier orbitals and therefore on the low-energy electronic excitations. The measuredelectronic transport energy gap (Eg= 1.85 eV) between the highest occupied molecular orbital (HOMO)and lowest unoccupied (LUMO) in TAPP is found to be significantly reduced with respect to TPP. More-over, an increased energy separation between the two highest occupied states (HOMO and HOMO−1) isfound both experimentally and by DFT calculations. Such evidence is attributed to an increased HOMOorbital destabilization due to an enhanced electron-donor character of the phenyl substituents uponamino functionalization. Finally, the above findings together with further time-dependent DFT calcula-tions are used to interpret the effect of the amino groups on the UV–Vis absorption spectrum, namely anoverall red-shift of the spectrum and remarkable intensity changes within the Q band.© 2017 Elsevier B.V.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The original PDF of the article can be found at : http://www.sciencedirect.com/science/article/pii/S0368204817300105
HAL Id:hal-01669998
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Dublin City University - DCU (IRELAND)
Other partners > Institut Supérieur d’Electronique et du Numérique - ISEN (FRANCE)
Other partners > Polytech'Marseille (FRANCE)
Other partners > Université de la Méditerranée - Aix-Marseille II (FRANCE)
Other partners > Universiti Sains Malaysia - USM (MALAYSIA)
Other partners > Université de Toulon - UTLN (FRANCE)
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Deposited By: Diane SAMELOR
Deposited On:21 Dec 2017 08:18

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