Titre :

Unraveling the Ground State and Excited State Structures and Dynamics of Hydrated Ce³⁺ Ions by Experiment and Theory

Auteur(s) :

Lindqvist-Reis, Patric [Auteur correspondant]
Institut für Nukleare Entsorgung [INE]
Réal, Florent [Auteur correspondant]
Physico-Chimie Moléculaire Théorique [PCMT]
Janicki, Rafał [Auteur]
Vallet, Valérie [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]

Titre de la revue :

INORGANIC CHEMISTRY

Pagination :

10111-10121

Éditeur :

American Chemical Society

Date de publication :

2018-08-09

ISSN :

0020-1669

Discipline(s) HAL :

Chimie/Chimie théorique et/ou physique
Physique [physics]/Physique [physics]/Chimie-Physique [physics.chem-ph]

Résumé en anglais : [en]

The 4f-5d transition of Ce³⁺ provides favorable optical spectroscopic properties such as high sensitivity and quantum yield, making it a most important dopant for lanthanide-activated phosphors. A key for the ...
Lire la suite >The 4f-5d transition of Ce³⁺ provides favorable optical spectroscopic properties such as high sensitivity and quantum yield, making it a most important dopant for lanthanide-activated phosphors. A key for the design of these materials with fine-tuned color emission is a fundamental understanding of the Ce³⁺ ground state and excited state structures and the dynamics of energy transfer. Such data is also crucial for deriving coordination chemistry information on Ce³⁺ ions in different chemical environments directly from their optical spectra. Here, by combining 4f-5d absorption and luminescence spectroscopy and highly accurate quantum chemical electronic structure calculations, we study the interplay between the local structure of Ce³⁺ in aqueous solutions and in crystalline hydrates, the strengths of Ce−O/Cl interactions with aqua and chloride ligands, and the resulting absorption and luminescence spectra. Experimental and theoretical absorption spectra of [Ce(H₂O)₉]³⁺ and [Ce(H₂O)₈]³⁺ with defined geometries provide a means for analyzing the equilibrium between these species in aqueous solution as a function of temperature (K(298) = 0.20 ± 0.03), while analyses of spectra of different aqua-chloro complexes reveal that eight-coordinate aqua-chloro complexes are present in solution at high chloride concentration. An intriguing feature in these systems concerns the large observed Stokes shifts, 5500−10 100 cm^-1. By exploring the excited state potential energy surfaces with relativistic multireference calculations, we show that these shifts result from significant geometrical relaxation processes in the lowest 5d1 excited state. For [*Ce(H₂O)₈]³⁺ the relaxation gives shorter Ce−O bonds and a Stokes shift of ∼5500 cm^-1, while for [*Ce(H₂O)₉]³⁺ the lowest 5d¹ state results in a spontaneous dissociation of a water molecule and a Stokes shift of ∼10 100 cm^-1. These findings are important for the understanding and optimization of luminescence properties of cerium complexes.Lire moins >

Langue :

Anglais

Vulgarisation :

Non

Projet ANR :

Physiques et Chimie de l'Environnement Atmosphérique

Collections :

• Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL