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Hitachi S-570 Lanthanum Hexaboride(LaB6) Emitter
Scanning Electron Microscope

The scanning electron microscope (SEM) is an important research tool in many areas of science and technology, and its magnification of ~10 X to over 500,000 X, great depth of field and resolution of a few nanometers to a few Angstroms are unequaled by other forms of microscopy. Using a crystal of LaB6 as the electron emitter instead of tungsten wire produces a brighter beam with a smaller sized electron source. This increases the resolution of the SEM, and allows the use of lower accelerating voltages, which helps prevent beam damage and penetration, and reduces charging artifacts.

SEMs are also unlike light microscopes or transmission electron microscopes in that a SEM never forms an image. Rather, electrons are generated from the specimen where the primary beam collides with the specimen. These generated secondary electrons are then drawn to a detector which collects them and produces a signal whose strength varies with the number of secondary electrons collected. This signal is then passed to the cathode ray tube whose beam is varied in synchrony with the signal from the detector. An image is then drawn on the CRT phosphor simply by the fluctuating strength of the CRT beam as it scans the phosphor. This signal may also be captured by a digital imaging system and stored as an image file in a computer. There are several other signals generated in the SEM by the beam - specimen interaction, all of which can be used to form an image by a similar mechanism, with an appropriate detector.

The Hitachi S-570 is a robust, relatively easy to use instrument capable of imaging a wide range of biological and materials samples. Imaging on our S-570 is by either secondary electrons or by backscattered primary beam electrons. Backscattered imaging is dependent on the average atomic number (Z) of the sample, and can be used to image, although not identify, different elements in a sample.

This is a service instrument for use by any group that needs it. The microscope can be operated by BBPIC staff, or investigators may be trained for independent use.