Word: cesium
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
Used in the Army's World War II snooperscopes, the image-converter is essentially a booster for light. In a vacuum tube, photons of light strike a cesium-antimony photocathode, which in turn gives off high-speed electrons. The electrons are accelerated through an electric field, hit a sensitive "retina" screen or a photographic plate, and etch out a crisp picture. Used in celestial photography, the image-converter proved impractical. Reason: water molecules in the photographic emulsion reacted with the cesium, destroyed the unshielded photocathode...
...university's Yerkes Observatory, he installed an aluminum shield, only four-millionths of an inch thick, between the photocathode and the photographic plate. The fast electrons passed right through the shield like light through a window; the foil prevented the water molecules from destroying the vulnerable cesium, hence the light booster could operate indefinitely...
...reduce this waste has been tried with some success by Astronomer Andre Lallemande of Paris (TIME, Aug. 13) 1951). Instead of using a photographic plate direct, he focused the light on a "photoemissive surface" of antimony and cesium, which gives off electrons when struck by light. The electrons jump to a photographic plate and expose it more efficiently than direct light does...
...image of the object to be photographed is first focused on a glass plate covered with an antimony and cesium compound, which gives off electrons when struck by light. At every point in the image electrons are knocked loose. Off to a slow start, they are whisked away at tremendous speeds by a powerful electric field. Then they are focused by a magnetic lens (as in an electron microscope) to form a new image on a photographic plate. The speeded-up electrons have taken energy from the electric field and form an image about 100 times stronger than the original...
...tiny high pressure laboratory, Professor Bridgman has produced forms of bismuth, gallium, calcium, strontium, barium, and cesium which have never been seen before. As in the case of red and yellow forms of sulfur that are seen under ordinary pressures, he has made forms of these elements that differ from their usual forms in appearance and in physical properties...