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Etude par détection de photons des processus électroniques au sein d'une jonction tunnel dans un milieu moléculaire

Abstract : Analysis of the luminescence induced by a STM (scanning tunneling microscope) permits to get insights into the electronic processes taking place in a single nanoscopic tunnel junction. We studied a Au(111)/Au junction under vacuum (UHV) and immersed in a molecular medium. The study under UHV reveals the influence of spatial variations of surface local density of states (LDOS) on the luminescence. The emission at the solid-liquid interface is characterized and the role played by the dielectric function is shown. Time correlations between the emitted single photons are then studied. Depending on the liquid immersing the junction, a photon bunching can occur. We link this bunching with structural changes of the junction induced by the presence of a diffusing molecule. If the HOMO-LUMO gap of the molecule is small enough, resonant tunnelling paths exist and tunnelling-electron bunching occurs. Finally, the influence of a self-assembled monolayer on the substrate is investigated. Boundings between triphenylene derivatives and Au(111) are too weak, but with chemisorbed alcanethiols, molecular resolution is reached both on the STM image and on the photon map. We show that the contrast on photon map comes from the modulation of the LDOS spatial extension into the barrier due to the S-Au bond. The elaboration of organic multilayers is considered as a route for observing the electroluminescence of a single molecule, isolated from the substrate by thiols and to study correlations of electronic origin. We have already optically characterised such a layer using C60.
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https://tel.archives-ouvertes.fr/tel-00008134
Contributor : Karen Perronet <>
Submitted on : Thursday, January 20, 2005 - 11:01:48 AM
Last modification on : Wednesday, May 2, 2018 - 4:52:01 PM
Long-term archiving on: : Friday, September 14, 2012 - 10:15:27 AM

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  • HAL Id : tel-00008134, version 1

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Karen Perronet. Etude par détection de photons des processus électroniques au sein d'une jonction tunnel dans un milieu moléculaire. Physique [physics]. Université Paris Sud - Paris XI, 2004. Français. ⟨tel-00008134⟩

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