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Thèse Année : 2004

Fragmentation d'agrégats de carbone neutres formés par collision atomique à haute vitesse

Résumé

The aim of this work is to understand the fragmentation of small neutral carbon clusters formed by high velocity atomic collision on atomic gas. In this experiment, the mainway of deexcitation of neutral clusters formed by electron capture with ionicspecies is the fragmentation. To measure the channels of fragmentation, a new detection tool based on shape analysis of current pulse delivered by semiconductor detectors has been developped. For the first time, all branching ratios of neutral carbon clusters are measured in an unambiguous way for clusters size up to 10 atoms.The measurements have been compared to a statistical model in microcanonical ensemble.In this model various structural properties of carbon clusters are required.These datas have been calculated with density functional theory to find the geometries of the clusters and then with coupled clusters formalism to obtain dissociation energies and other quantities needed to compute fragmentation model which has allowed to find an energy distribution deposited in the collision. Finaly specific cluster effect has been found namely a large population of excited states. This behaviour is completely different of the atomic carbon case with the electron capture in the ground states predominates.
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Dates et versions

tel-00008105 , version 1 (17-01-2005)

Identifiants

  • HAL Id : tel-00008105 , version 1

Citer

Guillaume Martinet. Fragmentation d'agrégats de carbone neutres formés par collision atomique à haute vitesse. Physique Nucléaire Théorique [nucl-th]. Université Paris Sud - Paris XI, 2004. Français. ⟨NNT : ⟩. ⟨tel-00008105⟩
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