Transmission Electron Microscopes
PHILIPS CM 100 Transmission Electron Microscope
PHILIPS CM 200 Transmission Electron Microscope
RECOMMENDED SAMPLE SIZE : Grid size is 3mm diameter, samples should be <100nm thick. Initial sample fixation for biological samples should not exceed 1mm³ (prior to sample dehydration & embedding). Contact us for protocols. RESOLUTION: CM100 - 0.24 nm, CM200 - 0.2nm. MAGNIFICATION: CM100 - 100,000x, CM200 - 2,000,000x
A transmission electron microscope (TEM) is comparable in design to an inverted light microscope. An electron gun at the top of the column produces a beam of electrons, which are accelerated down the column, and focused into a coherent beam by electromagnetic lenses onto the sample. The specimen, mounted on a small copper grid, must be thin enough to allow the beam to pass through it. The objective lens forms an image of the sample, which is further magnified by the imaging lenses below. The image is projected onto the fluorescent screen at the bottom of the column. In various positions in the column are a series of apertures, which serve to eliminate any stray electrons from the image forming process.
The interaction of the electron beam with the sample also generates other signals (e.g. X-rays) which can be used on the CM200 to give further information about the specimen using EDAX. X-rays generated by the interaction of the electron beam and sample are characteristic of the elements in the sample. The above example (Label A) is a spectrum obtained from the multi-layer coating on an ophthalmic lens, and shows the presence of silicon (Si) and oxygen (O) in the outer layer. The technique is non-destructive and is quantitative over the elemental range boron (B, Z=5) to uranium (U, Z=92). Software packages are available for particulate sizing and characterisation, and for elemental distribution maps.