SEM/EDX

Equipment : Scanning Electron Microscope - Philips XL30 ESEM
Detection modes available :
- SE: Secondary electrons with topography contrast.
- GSE: Secondary electron gas (presence of water vapor).
- BSE: Backscattered electrons with chemical contrast (heavy elements in clear on BSE images)
Sample : 6 "max., 50 mm X & Y
Resolution : 3.5 nm @ 30kV

Application domain

- Surface study (faults ...),

- Study of polished section (dimensioning of load, thickness of layers, etc.),

- Characterization of materials (elementary analysis of any element) ...

- Biology: Until now, the vacuum constraints imposed by scanning electron microscopy (the electrons must be accelerated under a high vacuum) constituted a handicap for many applications. For example, biological samples, hydrated, oily or insulating products which require observation in their natural state.

Principle

A SEM (Scanning Electron Microscope) uses an electron beam to obtain enlarged images of very good resolution. It can also be used to identify elements present in the sample thanks to their RX emission property in contact with electrons.
This is called energy dispersive microanalysis (EDS), in which the X emission is processed electronically. The energies of the peaks present are determined and they are automatically compared with an X emission file of known energies.
The analysis is qualitative but we can have access to relatively precise elementary contents.
The analyzes are carried out on raw samples or after metallization (increase in sensitivity).
The element detection threshold varies according to the analysis mode, it is around 500 ppm (0.05% w).