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Lecture L. Seijo

Rooster

WanneerWaar
08 mei 2008 FWN-Building 5114.0001, Nijenborgh 4, 9747 AG, Groningen
Speaker: Prof. Dr. L. Seijo
Affiliation: Universidad Autonoma de Madrid, Spain
Title: Embedded cluster calculations on excited local states of lanthanide and actinide ions in solids
Date: Thu May 8, 2008
Start: 13.30
Location: FWN-Building 5114.0001
Host: R. Broer
Telephone: +31 50 363 4374

Abstract

Wave function based ab initio techniques of molecular quantum chemistry are used in embedded cluster calculations of lanthanide and actinide ions in solids. Explicit considerations of electron correlations, relativistic effects up to spin-orbit coupling, and embedding effects of the solid hosts are made by means of approximate, though accurate methods, which turn the computations of large manifolds of local excited states affordable. As a result, absorption and emission spectra are modelled with an accuracy good enough so as to provide interpretations of experimental spectra hard to obtain by other means. As a consequence, lanthanide-based luminescent materials useful in Solid-State Lighting (SSL) devices and actinide-based materials related to Advanced Nuclear Energy Systems (ANES) are being under study from the point of view of theoretical ab initio calculations.

The following results are presented: The blue absorption and the yellow luminescence of the phosphor Ce(3+)-doped YAG, which is used in commercial SSL devices; the prediction and confirmation of bond length shortening upon the lowest 4f→5d and 5f→6d excitations; and the > detailed interpretations of the 5f →6d absorption spectra of U(4+)-doped and U(3+)-doped Cs2NaYCl6.

 

Laatst gewijzigd:22 oktober 2012 14:30