The image gas atoms in the vicinity of the specimen are polarized because of the high field and then attracted to the apex region of the specimen. After a series of collisions with the specimen during which the image gas atoms lose part of their kinetic energy, these image gas atoms become thermally accommodated to the cryogenic temperature of the specimen. If the field is sufficiently high, these image gas atoms are field ionized by a quantum-mechanical tunneling process. The ions produced are then radially repelled from the surface of the specimen towards the microchannel plate and screen assembly. A microchannel plate image intensifier positioned immediately in front of the phosphor screen produces between 103 and 104 electrons for each input ion. These electrons are accelerated towards the phosphor screen where they produce a visible image.
The field-ion microscope was invented by Erwin Müller in 1951 at Pennsylvania State University.
Related category• INSTRUMENTATION
Source: National Institute for Materials Science (Japan)
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