Caesium iodide
| Caesium iodide | |
| Names | |
|---|---|
| IUPAC name
Caesium iodide
|
|
| Other names
Cesium iodide
|
|
| Identifiers | |
7789-17-5  [1] |
|
| ChemSpider | 23003 |
| EC Number | 232-145-2 |
| Jmol 3D model | Interactive image |
|
|
|
|
| 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)
|
1.739 |
| Structure | |
| CsCl | |
| Pm3m, No. 221 | |
|
a = 456.67 pm
|
|
| Cubic (Cs+) Cubic (I−) |
|
| Vapor pressure | {{{value}}} |
| Related compounds | |
|
Other anions
|
Caesium fluoride Caesium chloride Caesium bromide Caesium astatide |
|
Other cations
|
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).
|
|
 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]
