What's difference should be considered to prepare a sample surface to test SEM and BSE?
Scanning Electron Microscopes (SEM) and Backscattered electrons (BSE)
The BSE test requires a smoother surface than the SEM test.
What must consider for cutting, polishing, and coating of the samples such as cement paste? When we wanting results of SEM and BSE test with high quality.
Dear Hossein,
SEM defines electrons with energies below 50 eV. Because the penetration depth (here exit depth, not excitation depth) of these low energy secondary electrons is very low (some Angström), the purity of the surface must be very high. Otherwise you characterize the properties of the surface layer due to contaminations.
The backscattered electrons have energies in the keV range. These backscattered electrons (Rutherford backscattering) arise from higher depths. A contamination is less relevant for BSE than for SEM. You can detect different atomic numbers (atomic number contrast) and topography. For topography contrast you need 2 detectors to measure a difference signal. Therefrom is clear: Residual paste gives the wrong atomic number contrast.
With Regard
R. Mitdank
For both SE (secondary electrons) and BSE (backscattered electrons) you can use polished, fractured or "as is" surface. It depends on your task. So, if you need advise on specimen preparation, you should describe your problem in more detail. Contamination problem in most cases is not important. Do not bother with topographical contrast in BSE, it is much worse than SE image.
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