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Analysis with TEM
With the help of TEM, materials can be analysed on the nanometer- to micrometer-scale, which can be useful either as a complementary technique or as preparation and sample screening before experiments at large scale research infrastructure facilities.
Purpose
Using transmission electron microscopy (TEM) we can analyse the structure of materials on length scales from several micrometres down to the atomic scale. We can image both soft materials like gels, emulsions, food or polymers, and hard materials like metals or concrete.
TEM is well suited as a complementary method to large-scale research infrastructure techniques, as it can be used to analyse specimens with high resolution in a conventional lab environment.
Method
Specimen preparation
Since TEM requires thin specimens with a thickness of around 100 nm, specimen preparation is as important as the actual analysis. That is why we have equipment and competence for advanced specimen preparation of water- and fat-containing samples. Those include freeze fracturing, mica sandwich technique, plunge freezing, plastic embedding at -90°C or room temperature, and thin-slicing.
JEOL JEM-2100Plus
This TEM can be used for imaging of almost all types of materials but is optimised for soft materials and good image quality on low-contrast specimens. The high voltage can be varied between 80 and 200 kV, depending on the beam sensitivity of the specimen and requirements for resolution and contrast. At 200 kV the microscope reaches a resolution of 0.14 nanometre. Even scanning transmission electron microscopy (STEM) can be performed with a resolution of 1 nanometre.
Beam-sensitive specimens
The microscope is equipped with a TVIPS TemCam-XF416ES CMOS camera. This camera delivers high-resolution images with low levels of noise, high contrast and high framerates, and is therefore optimally suited for soft materials and beam-sensitive specimens. The software is designed for imaging with low electron dose, so that the beam is only on the specimen while an image is taken.
3D imaging
Specimens can be analysed in three dimensions using tomography. The specimen is rotated between ± 70 degrees and the images are reconstructed using an advanced software to obtain a 3D model of the structure.
Cryo TEM
Water-containing samples, e.g., diluted solutions of nanoparticles, liposomes, fibres or micelles, can be vitrified (frozen) in liquid ethane and analysed using a dedicated cryo TEM specimen holder at around -180 °C. Even 3D tomography can be performed at cryogenic temperature.
Crystal structure
With electron diffraction the crystal structure of a sample or the degree of crystallinity in a heterogeneous sample can be probed locally. The crystal structure can even be used to manipulate the image contrast through bright-field- and dark-field imaging.
Delivery
Measurement data (image sequences) and a report (Powerpoint) containing an analysis of the results. Of course, we adapt the delivery based on your requests and needs.
