Caesium bromide or cesium bromide is an ionic
compound of
caesium
Caesium (IUPAC spelling; also spelled cesium in American English) is a chemical element; it has Symbol (chemistry), symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of , which makes it one of only f ...
and
bromine
Bromine is a chemical element; it has chemical symbol, symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between th ...
with the
chemical formula
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...
CsBr. It is a white or transparent solid with melting point at 636 °C that readily dissolves in water. Its bulk crystals have the cubic CsCl structure, but the structure changes to the
rocksalt type in nanometer-thin film grown on
mica
Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as ''perfect basal cleavage''. Mica is co ...
, LiF, KBr or NaCl substrates.
Synthesis
Caesium bromide can be prepared via following reactions:
*
Neutralization:
: CsOH (aq) + HBr (aq) → CsBr (aq) + H
2O (l)
: Cs
2(CO
3) (aq) + 2 HBr (aq) → 2 CsBr (aq) + H
2O (l) + CO
2 (g)
* Direct synthesis:
: 2 Cs (s) + Br
2 (g) → 2 CsBr (s)
The direct synthesis is a vigorous reaction of caesium with bromine. Due to its high cost, it is not used for preparation.
Uses
Caesium bromide is sometimes used in optics as a
beamsplitter component in wide-band
spectrophotometers
Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. Spectrophotometry uses photometers, known as sp ...
.
References
Crystran Ltd experimental data July 2021
Cited sources
*
External links
,
Ultra-violet photoabsorption measurements in alkali iodide and caesium bromide evaporated films
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Caesium compounds
Alkali metal bromides
Caesium chloride crystal structure