Scanning Electron Microscopy (SEM)

Diatom

Scanning electron microscopy (SEM) enables imaging of a surface using an electron beam. The electron beam interacts with the surface of the sample and by using a variety of detectors topographic images, atomic-number (Z) contrast images, element composition and fluorescence information can be obtained from the specimen.

In our electron microscopy (EM) suite we have two scanning electron microscopes (SEMs) and an environmental scanning electron microscope (ESEM) which provide a range of analytical techniques. Our capabilities include:

  • Digital imaging over a range of magnifications depending on sample quality (~ X20 to X300 000), in the following modes
    • secondary electron emission (SEI) - ideal for materials with surface relief and/or multiple faces
    • backscattered electron (BSE) - best suited to thin section work
    • cathodoluminescence (CL) - samples must contain luminescent elements and be thin section form
  • Energy Dispersive X-ray Spectroscopy (EDS or EDX)
    • EDX detectors allow the ID and semi-quantification of elements from carbon (C) upwards
    • output is in the form of spot/point data, average area measurements or single element digi-mapping (using X-ray intensity distribution)
  • Low vacuum (LV) mode for sensitive samples or those not appropriate for carbon or gold coating (typically used to improve conductivity)

Samples

  • Your samples should all be clearly labelled with unique identifiers
  • Dry powder and material samples are usually best stored in glass containers and not in plastic bags or bottles (as plastics are prone to static and some can contaminate samples)
  • Disposal - we will dispose of all unclaimed samples after three months from analysis completion

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