Electronic excited states of planar vs bowl-shaped polycyclic aromatic hydrocarbons in interaction with water clusters: a TD-DFT study
Résumé
In an astrochemical and environmental context, this work constitutes a step forward in understanding the photo-reactivity of polycyclic aromatic hydrocarbons (PAHs) with water molecules and in water ice under irradiation with low energy photons. The role of charge transfer states PAH +-H 2 O − has been proposed, motivating the study of the electronic excited states up to about 6 eV of planar and bowl-shaped PAHs, namely pyrene C 16 H 10 and corannulene C 20 H 10 , interacting with water clusters of different sizes and orientations, using a time-dependent density functional theory approach. In the case of pyrene, the systematic occurrence of low energy excitations from π orbitals to diffuse orbitals located on some water molecules, mixed with the Rydberg orbitals (R/wat), was found. Such excitations are more numerous and possess larger oscillator strengths when (i) the number of water molecules increases up to representing a first layer of hexagonal water ice and (ii) for the arrangements leading to the lower vertical ionisation potential values. In this case, the /wat orbitals are located on the most external H atoms and they may
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Chimie théorique et/ou physiqueOrigine | Fichiers produits par l'(les) auteur(s) |
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