In a Transmission Electron Microscope (TEM) a beam of electrons is emitted from an electron gun and accelerated to an energy of typically 80-300 keV. An array of magnetic lenses focuses the electrons into a small probe that is transmitted through the sample. Another set of lenses then forms either an image of the specimen, or a diffraction pattern, using the transmitted electrons. TEM is the only experimental technique that allows for imaging and chemical analysis with sub-Å resolution and it has been applied in many different research fields ranging from materials science to life science.
The TEM 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. 2D and 3D imaging of the structures is possible as well as the mapping of electric and magnetic fields. As a rule of thumb TEM requires samples with a thickness of less than 100 nm. Furthermore, since the microscope operates under high vacuum samples have to be dry and they also need to withstand the exposure to the high energy electron beam. Sample preparation is an essential part of the technique.
Chalmers Materials Analysis Laboratory (CMAL) has three different TEMs including a state-of-the-art Titan 80-300 equipped with a probe corrector and a monochromator. The probe corrector allows for a focused electron probe with a diameter of around 0.7 Å, i.e. less than the size of an atom, for atomic resolution imaging and chemical analysis. The monochromator allows for chemical analysis through electron energy loss spectroscopy (EELS) with an energy resolution of around 150 meV. In addition, chemical analysis may also be performed with energy dispersive X-ray analysis. The latest TEM, the double-corrected JEOL MonoNEOARM200F, includes an improved monochromator that ensures an energy resolution of down to 20 meV, the latest generation of image filter for faster data acquisition, and a higher resolution camera for higher quality and faster image acquisition. For further information see specific details for each instrument.
• LaB6 thermionic emission electron gun
• EDAX EDS
• Orius 200 CCD
• Schottky field emission gun
• Probe Cs-corrector
• GIF Tridiem 866
• Oxford X-sight EDS
• Schottky field emission electron gun
• Probe and image Cs-correctors
• GIF Continuum HR
• Dual EDX and EELS
• Electron holography
• Tomography, cryo, heating, liquid and biasing in-situ holders
• OneView camera