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XAS-XEOL and XRF spectroscopies using Near-Field Microscope probes for high-resolution photon collection

Abstract : Scanning Probe Microscopes allow to obtain sample topography up to atomic resolution. Local surface properties such as potential, elasticity, density of states... can also be determined. However, an a priori knowledge of the sample chemistry is required to completely identify the objects present on the sample surface. X-ray spectroscopies allow elemental and structural analysis of a sample with accuracy better than 1 Å. The lateral resolution is limited by the primary beam diameter, currently a few μm². Two different ways can be followed to enhance the lateral resolution: - further primary beam focusing - detector aperture shrinking to collect the fluorescence coming only from a part of the emitting volume, while keeping a significant signal/noise ratio. This is ensured approaching the detector as much as possible toward the surface. We have chosen to develop this second option. Local sample visible luminescence is collected through a low aperture sharp optical fibre, probe of a shear force microscope. This technique was used to characterize microstructured semiconducting samples to achieve simultaneously the surface topography and luminescence mapping. The results were obtained using either synchrotron radiation or a laboratory microsource equipped with a polycapillary lens. To extend this concept to a wider variety of materials, local XRF collection by an EDX detector equipped with a cylindrical X-ray capillary was tested. A cobalt sample irradiated with the microsource was used for technique evaluation. The signal magnitude dependence with the capillary diameter was measured. Modelling and numerical calculations were developed to estimate the signal magnitude that could be detected using a 1 μm diameter capillary. The optimal system geometry was determined. Scanning Probe Microscopy combined to XRF analysis could thereby lead to simultaneous acquisition of sample topography and chemical mapping. The expected lateral resolution using synchrotron radiation is 100 nm while sub 1 μm resolution is realistic with a laboratory source. This technique would allow to point a peculiar micro- or nano-object on the surface and to perform its chemical analysis.
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https://tel.archives-ouvertes.fr/tel-00880623
Contributor : Maël Dehlinger <>
Submitted on : Wednesday, November 6, 2013 - 3:09:59 PM
Last modification on : Thursday, January 18, 2018 - 2:25:35 AM
Long-term archiving on: : Friday, February 7, 2014 - 9:45:10 AM

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  • HAL Id : tel-00880623, version 1

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Maël Dehlinger. XAS-XEOL and XRF spectroscopies using Near-Field Microscope probes for high-resolution photon collection. Science des matériaux [cond-mat.mtrl-sci]. Aix-Marseille Université, 2013. Français. ⟨tel-00880623⟩

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