Consultancy Service - Electron Miscroscopy (Materials Characterisation)

The CREST facility houses a Jeol 8600 microprobe. The essential parts of the electron microprobe are:

• Electron gun and a system of electromagnetic lenses for producing a focused beam and scanning coils to allow the beam to raster across the specimen.
• Specimen stage with X-Y-Z movement.
• Detection system.

The detection systems on the probe include two wavelength dispersive spectrometers and an EDAX light element capable energy dispersive spectrometer. Electron probe microanalysis is used for chemical analysis of micro-volumes at the surface of polished solid specimens utilising a fine beam of electrons to bombard the surface of the specimen. The electron beam generates x-rays whose wavelength (WDS) or energy (EDAX) is characteristic of the elements present in the sample. The intensities of the x-ray are a measure of the proportions of the elements present. Quantitative analysis using wavelength dispersive spectrometry requires both a stable, well tuned instrument and standards for comparison that are both well characterised and appropriate to the given specimen. Quantitative analysis can address all elements heavier the lithium. The attached EDS system in addition allows any element to be map on the specimen.

The microprobe also functions as a scanning electron microscope. In addition to elemental analysis capability, images from secondary electrons (SEI) and back scattered electrons (BSI) can be produced. The SEM images the surface (topography) of virtually any solid material or biological sample. Hard copy and digital imaging can be produced using the Semafore digitizer attached which gives high quality digital images making it easy to store and retrieve images from a database.