Caesium iodide
Caesium iodide | |
Names | |
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IUPAC name
Caesium iodide
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Other names
Cesium iodide
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Identifiers | |
7789-17-5 [1] | |
ChemSpider | 23003 |
EC Number | 232-145-2 |
Jmol 3D model | Interactive image |
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Properties | |
CsI | |
Molar mass | 259.81 g/mol |
Appearance | white crystalline solid |
Density | 4.51 g/cm3, solid |
Melting point | 621 °C (1,150 °F; 894 K) |
Boiling point | 1,277 °C (2,331 °F; 1,550 K) |
440 g/L (0 °C) | |
Refractive index (nD)
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1.739 |
Structure | |
CsCl | |
Pm3m, No. 221 | |
a = 456.67 pm
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Cubic (Cs+) Cubic (I−) |
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Vapor pressure | {{{value}}} |
Related compounds | |
Other anions
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Caesium fluoride Caesium chloride Caesium bromide Caesium astatide |
Other cations
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Lithium iodide Sodium iodide Potassium iodide Rubidium iodide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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verify (what is ?) | |
Infobox references | |
Caesium iodide (chemical formula CsI) is the ionic compound of caesium and iodine. It is often used as the input phosphor of an x-ray image intensifier tube found in fluoroscopy equipment. Caesium iodide photocathodes are highly efficient at extreme ultraviolet wavelengths.[2]
An important application of caesium iodide crystals, which are scintillators, is electromagnetic calorimetry in experimental particle physics. Pure CsI is a fast and dense scintillating material with relatively high light yield. It shows two main emission components: one in the near ultraviolet region at the wavelength of 310 nm and one at 460 nm. The drawbacks of CsI are a high temperature gradient and a slight hygroscopicity.
Caesium iodide is used as a beamsplitter in Fourier transform infrared (FTIR) spectrometers. It has a wider transmission range than the more common potassium bromide beamsplitters, extending its working range into the far infrared. However, optical-quality CsI crystals are very soft and a hard to cleave or polish. They should also be coated (typically with germanium) and stored in a desiccator, to minimize interaction with atmospheric water vapors.[4]
Caesium iodide atomic chains can be grown inside double-wall carbon nanotubes. Accurate measurements reveal that in such chains I atoms appear brighter than Cs atoms despite having a smaller mass. This difference was explained by the charge difference between Cs atoms (positive), inner nanotube walls (negative) and I atoms (negative). As a result, Cs atoms are attracted to the walls and vibrate more strongly than I atoms, which are pushed toward the nanotube axis.[3]