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Etude théorique et simulations de petites molécules de sodium excitées, immergées dans des matrices d'argon.

Abstract : The purpose of this work is to understand how a rare gas environment can modify the static and dynamic properties of small sodium molecules. The chosen system has physical and chemical properties which permit a two-levels description where only the valence electrons of the molecule are explicitly treated within quantum mechanics.
The electronic structure is calculated using the configurations interaction method while sodium ions and argon atoms are treated within classical molecular dynamics of polarizable atoms. The theoretical model allows determining the equilibrium geometry and the optical properties of the sodium atom and dimers embedded in argon matrices. The most stable trapping site depends on the electronic charge of the dimer as was found dynamically by removing an electron from embedded Na2 and relaxing the system.
For Na2+, we highlight the role of the matrix size on the non-adiabatic dynamics on the first excited state (X-> A) which is dissociative in gas phase. We show that there exists a critical number of argons which prevents the dissociation of the dimer due to a translation along the insertion row. This translation, observed for larger systems, is avoided when including the non-adiabatic couplings within a surface hopping algorithm. In this case, we observe a non-radiative desexcitation of the dimer towards its fundamental state after a few picoseconds.
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https://tel.archives-ouvertes.fr/tel-00264921
Contributor : Julie Douady <>
Submitted on : Tuesday, March 18, 2008 - 11:58:52 AM
Last modification on : Monday, December 9, 2019 - 12:32:08 PM
Long-term archiving on: : Thursday, May 20, 2010 - 10:11:18 PM

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  • HAL Id : tel-00264921, version 1

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Julie Douady. Etude théorique et simulations de petites molécules de sodium excitées, immergées dans des matrices d'argon.. Physique Atomique [physics.atom-ph]. Université de Caen, 2007. Français. ⟨tel-00264921⟩

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