5. Induced side effects

5.1 Electrically insulating samples

In the case of samples with low electrical conductance, the accumulation of charges brought by the beam, localized on the surface, can lead to discharges towards the conductive support or the walls of the analysis chamber itself. These discharges are sources of X-ray continuum emission, via the violent acceleration/deceleration of secondary electrons in the induced plasma, which is superimposed on the X-ray spectrum. This parasitic background generally appears throughout the spectrum, but becomes the dominant source in the high-energy region, greatly degrading the signal-to-noise ratio in this area. To avoid this problem, it is usually sufficient to connect the surface of the insulating sample to the substrate using a good conductor, thus encouraging...