The Scanning X-ray microscope can be operated in an energy range from 2-9 keV, thus giving access to the K-edges of Phosphorus to Copper, and to the L- and M-edges of some heavier elements for micro-fluorescence and micro-XANES measurements. Please consult the following periodic table for further details. The wide spectral operating range of the microscope is attractive for spectro-microscopy. Whilst in its simplest form the microscope allows taking multiple images of a single sample region at different incident energies, it also offers the possibility to perform highly spatially resolved XANES scans on small regions of the sample.

A fixed exit double crystal monochromator equipped with Si<111>, Si<220> crystals or NiB4C multilayers is used to select and/or scan the energy of the x-ray beam.

The monochromatic beam is then focused to a submicron probe using a Fresnel zone plate. Typically, the spot size varies between 0.2 to 1 micron depending on the energy, with a beam flux of the order of 108- 109 photons/s/Si<111> bandwidth. The rejection of unwanted focusing orders of the zone plate is ensured by the combined use of a central stop and an Order Selecting Aperture (OSA). The microscope underwent a major refurbishment in 2008 and can now host a Kirkpatrick-Baez mirrors system to focus the beam down to 0.35 x 0.7 µm2 with a photon flux of 1010-1011 photons/s/Si<111>.

The sample is aligned in the focal plane of the zone plate and raster scanned in the micro-beam to collect 2D images. Silicon photodiodes are used for transmission measurements. The SXM is also equipped with several energy dispersive detectors, a single or a 7-element high purity germanium detector (HpGe) from Princeton Gamma-Tech (US) and a Silicon Drift Diode (SDD) XFLASH 5100 from Bruker (Germany). Transmission signal as well as a full fluorescence spectrum can be recorded for each pixel of the map.

 

For further technical details, please consult the page dedicated to the SXM II end-station.