Electron Microprobe

Cameca SX 100 Electron Microprobe

The Cameca SX 100 Electron Microprobe is a fully digitized instrument with highly integrated electronics and full automation which can be set up for unattended analysis and evaluation. This instrument has a standard tungsten electron emitter which produces a beam of electrons of tuneable energy focussed onto the surface of the sample, exciting a volume of ca. 1 µm3. The sample can be moved across the beam in the perpendicular plane, to analyse a selected number of sites. There are five wavelength dispersive detectors, each equipped with a choice of diffracting crystals, allowing simultaneous quantitative analyses of up to five different elements at chosen points across the sample, at a special resolution of ca. 1 µm.

 

The spectrometer can be programmed to run a series of scans for different combinations of elements, giving a comprehensive elemental analysis of the surface

There is also an energy dispersive detector, used to collect fluorescence spectra allowing identification at each point selected of all the elements present with a fluorescence line at lower energy than the electron beam. The spectrometer can also be set up to map the relative concentrations (non-quantitatively) of up to four elements at a time (or five elements with fewer pixels per map) across a raster of 512 x 512 pixels in a selected area.

The instrument is equipped with an optical microscope which can be centred on the focal point of the electron beam in order to identify areas to sample. It has continuous zoom (from 250 µm to 1.7 mm field) for ease of location of points of interest in inhomogeneous samples.

Samples should be flat, for example a thin section, and must be coated with a thin film of carbon before being introduced into the spectrometer. All measurements take place in a vacuum, therefore volatile samples cannot be used.

 

Location: Room B10, illiamson Building |  Member of staff: Dr John Charnock

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