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Microscopie ionique à projection à partir d'une source à structure coaxiale

Abstract : This study is about a coaxial structure ion source based on field ionization. This source is made of an ultra-sharp nanometer size metal tip. The tip is inserted inside a capillary. Gas is supplied onto the tip from a high pressure chamber. This gas is field ionized at the tip apex in an ultra high vacuum chamber. High pressure by the tip results from this structure, keeping a low pressure in the ultra high vacuum chamber where ions therefore freely propagate. Measurements of this local pressure shows a 106 times higher value than that in the ultra high vacuum chamber. This measurement is performed for various flowing regimes inside the capillary and for various gases. The source runs either at room temperature or at lower temperature.
Identification of ions produced from tips made of W, Pt and Pd and for H2, H2O and their mixtures results from mass spectrometry with a home-made instrument. The great variety of produced ions is relevant from a nanometer scale physico-chemistry.
A projection microscope incorporating this source has been built. X 500 000 magnifications and 3 Å resolution were achieved. Beyond the obvious interest of such a microscopy, this proves an ion source virtual size of less than 3 Å opening interesting outlooks in ion optics like FIB for instance.
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https://tel.archives-ouvertes.fr/tel-00275122
Contributor : Marion Descoins <>
Submitted on : Tuesday, April 22, 2008 - 3:19:55 PM
Last modification on : Thursday, January 18, 2018 - 1:38:21 AM
Long-term archiving on: : Friday, May 21, 2010 - 1:56:38 AM

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  • HAL Id : tel-00275122, version 1

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Marion Descoins. Microscopie ionique à projection à partir d'une source à structure coaxiale. Physique [physics]. Université Paul Cézanne - Aix-Marseille III, 2007. Français. ⟨tel-00275122⟩

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