Scanning Electron Microscopy (SEM)

In a Scanning Electron Microscope (SEM) a beam of electrons is emitted from an electron gun and accelerated to an energy up to typically 30 keV. An array of magnetic lenses focuses the electrons into a small probe that is scanned across the sample. A set of different detectors is used for picking up and forming an image of the different signals generated from the interaction of the beam with the sample. The most common imaging modes are to form either topographic or atomic contrast images. SEM has been applied in many different fields ranging from materials science to life science.

The SEM is used for obtaining image and chemical information about the nano and microstructure of all types of materials, ranging from metals and ceramics to soft biomaterials. Samples need to be electrically conducting but with the use of an ESEM wet samples may also be analysed.

Chalmers Materials Analysis Laboratory has three different SEMs:

The LEO Ultra 55 is used for high resolution imaging of conducting samples. It is also equipped with an EDX (energy dispersive X-ray) detector for chemical analysis, an EBSD (electron backscattered diffraction) detector for grain orientation and texture analysis, and a STEM (scanning transmission electron microscopy) detector for thin foil analysis.

The JEOL JSM-7800F Prime is used for high resolution imaging but can also be used in low vacuum mode. It is equipped with an EDX detector and a SXES (Soft X-ray emission spectrometer), the latter used for analysis of low-energy X-rays (typically 50 -200 eV).

The FEI Quanta 200 ESEM (environmental SEM) allows for imaging of non-conducting samples as well as wet samples at a high chamber pressure. Heating and cooling experiments may be performed in-situ in the ESEM as well.

LEO Ultra 55

Quick facts:
•    Operating voltage: 0.1 - 30 kV
•    Field emission gun
•    Equipped with:
     - Oxford Inca EDX system
     - EBSD system

JEOL JSM-7800F Prime

Quick facts:
•    Field emission gun
•    Operating voltage: 500 V (10 V using a biased sample) to 30 kV
•    Oxford X-Max 80 mm2 detector
•    SXES (Soft X-ray emission spectrometer)

FEI Quanta200 ESEM

Quick facts:
•    Operational vacuum modes: HV, LV and ESEM
•    Operating voltage: 0.5-30kV
•    Field emission gun
•    Equipped with:
     - Oxford X-max 80 EDX
     - Peltier stage (-20°C - +100°C)
     - Heating stage (1000°C)
     - Cathodoluminescence

Published: Thu 22 Jun 2017.