|This article needs additional citations for verification. (September 2014)|
|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||1277±5 °C|
|44 g/100 ml (0 °C)|
Refractive index (nD)
|Pm3m, No. 221|
a = 456.67 pm
|EU Index||not listed|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
|2386 mg/kg (oral, rat)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is: / ?)(|
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.
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 can be used in Fourier Transform Infrared (FT-IR) spectrometers as a beamsplitter. CsI has a wider transmission range than the more common potassium bromide beamsplitters, extending its usefulness into the far infrared. A problem with optical-quality CsI crystals is that they are very soft with no cleavage, making it difficult to create a flat polished surface. Also, the CsI optical crystals must be stored in a desiccator to prevent water damage to the surfaces, and coated (typically with germanium) to minimise water damage from short term atmospheric exposure during beamsplitter swapouts.
- Transmission range: 250 nm to 55 µm
- Refractive index: 1.739 at 10.6 µm
- Reflection loss: 13.6% @ 10.6 µm (2 surfaces)
- Hardness (Knoop): 137.9 kPa (20 lbf/in2)
- Young's modulus: 5.3 GPa (769 lbf/in2)
- Modulus of rupture: 5.6 GPa (810 lbf/in2)
- Apparent elastic limit: 5.6 GPa (810 lbf/in2)
- Structure: Cubic, no cleavage
- color: colorless
- M. P. Kowalski,G. G. Fritz, R. G. Cruddace, and A. E. Unzicker, and N. Swanson, Quantum efficiency of cesium iodide photocathodes at soft x-ray and extreme ultraviolet wavelengths, Applied Optics, retrieved July 2012