Structure and electronic properties of quinizarin chemisorbed on alumina

authored by: Irmgard Frank, Dominik Marx, Michele Parrinello
Abstract: The anthraquinone dye molecule quinizarin is known to allow for persistent spectral hole burning up to liquid nitrogen temperatures after chemisorption on alumina surfaces. The mechanism underlying these improved hole-burning properties is not known, though is has been speculated that it might be related to intrinsic surface effects on the electronic structure of the dye. We approach this problem theoretically using gradient corrected density functional theory. The chemisorbed compound system is modelled by a periodically replicated nine layer slab which represents the (0001) surface of α-Al₂O₃. The chemisorption geometry obtained by geometry optimization and confirmed by Car-Parrinello molecular dynamics runs at room temperature is shown to be a perpendicular arrangement of quinizarin on the surface, where a chelate-like bond is formed with one exposed surface aluminum atom. In order to get information about the electronic structure, the frontier orbitals that are relevant for the description of the electronic excitation to the first excited state are evaluated for the isolated molecule, the chemisorbed molecule, and a quinizarin-aluminum-water complex. The strong red shift of the absorption frequency found in experiment upon chemisorption is reproduced. However, the results show that the shape of the frontier orbitals and hence the properties of the electronic excitation remain essentially unchanged by chemisorption. Thus, the differences in the behavior of the isolated and the chemisorbed dye observed in persistent spectral hole-burning experiments cannot be explained by genuine surface induced effects on the molecular electronic structure.
External Organisation(s): University of Bonn
Max Planck Institute for Solid State Research (MPI-FKF)
Type: Article
Journal: Journal of Chemical Physics
Volume: 104
Pages: 8143-8150
No. of pages: 8
ISSN: 0021-9606
Publication date: 22.05.1996
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: General Physics and Astronomy, Physical and Theoretical Chemistry
Electronic version(s): https://doi.org/10.1063/1.471490 (Access: Closed)

BibTeX

@article{2c5d92ed1c9b4e7e82450e430f6b2d92,
title = "Structure and electronic properties of quinizarin chemisorbed on alumina",
abstract = "The anthraquinone dye molecule quinizarin is known to allow for persistent spectral hole burning up to liquid nitrogen temperatures after chemisorption on alumina surfaces. The mechanism underlying these improved hole-burning properties is not known, though is has been speculated that it might be related to intrinsic surface effects on the electronic structure of the dye. We approach this problem theoretically using gradient corrected density functional theory. The chemisorbed compound system is modelled by a periodically replicated nine layer slab which represents the (0001) surface of α-Al2O3. The chemisorption geometry obtained by geometry optimization and confirmed by Car-Parrinello molecular dynamics runs at room temperature is shown to be a perpendicular arrangement of quinizarin on the surface, where a chelate-like bond is formed with one exposed surface aluminum atom. In order to get information about the electronic structure, the frontier orbitals that are relevant for the description of the electronic excitation to the first excited state are evaluated for the isolated molecule, the chemisorbed molecule, and a quinizarin-aluminum-water complex. The strong red shift of the absorption frequency found in experiment upon chemisorption is reproduced. However, the results show that the shape of the frontier orbitals and hence the properties of the electronic excitation remain essentially unchanged by chemisorption. Thus, the differences in the behavior of the isolated and the chemisorbed dye observed in persistent spectral hole-burning experiments cannot be explained by genuine surface induced effects on the molecular electronic structure.",
author = "Irmgard Frank and Dominik Marx and Michele Parrinello",
year = "1996",
month = may,
day = "22",
doi = "10.1063/1.471490",
language = "English",
volume = "104",
pages = "8143--8150",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics",
number = "20",
}