:Caesium iodide

{{chembox

| Watchedfields = changed

| verifiedrevid = 476994560

| Name = Caesium iodide

| ImageFile =Kristall CsI(Tl).jpg

| ImageCaption =CsI crystal

| ImageFile1 =Kristall-CsI(Tl) mit Skala.jpg

| ImageCaption1 =Scintillating CsI crystal

| ImageFile2 = CsCl polyhedra.png

| ImageCaption2 =Crystal structure

| ImageSize2 =

| ImageFile3 = Caesium-iodide-3D-ionic.png

| ImageName = Caesium iodide

| IUPACName = Caesium iodide

| OtherNames = Cesium iodide

|Section1={{Chembox Identifiers

| InChI = 1/Cs.HI/h;1H/q+1;/p-1

| SMILES = [Cs+].[I-]

| InChIKey = XQPRBTXUXXVTKB-REWHXWOFAA

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/Cs.HI/h;1H/q+1;/p-1

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = XQPRBTXUXXVTKB-UHFFFAOYSA-M

| CASNo = 7789-17-5

| CASNo_Ref = {{cascite|correct|CAS}}[https://chem.nlm.nih.gov/chemidplus/rn/7789-17-5 Cesium iodide]. U.S. National Library of Medicine

| EC_number = 232-145-2

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 23003

| PubChem = 24601

| RTECS = FL0350000

| UNII = U1P3GVC56L

}}

|Section2={{Chembox Properties

| Formula = CsI

| MolarMass = 259.809 g/mol

| Appearance = white crystalline solid

| Density = 4.51 g/cm³

| Solubility = 848 g/L (25 °C)

| MeltingPtC = 632

| BoilingPtC = 1280

| MeltingPt_ref =Haynes, p. 4.57

| BoilingPt_ref =

| RefractIndex = 1.9790 (0.3 µm)
1.7873 (0.59 µm)
1.7694 (0.75 µm)
1.7576 (1 µm)
1.7428 (5 µm)
1.7280 (20 µm)Haynes, p. 10.240

| MagSus = −82.6·10⁻⁶ cm³/molHaynes, p. 4.132

}}

|Section3={{Chembox Structure

| CrystalStruct = CsCl, cP2

| SpaceGroup = Pm{{overline|3}}m, No. 221{{cite journal|doi=10.1103/PhysRevB.29.1112|title=Equation of state and high-pressure phase transition of CsI|journal=Physical Review B|volume=29|issue=2|pages=1112|year=1984|last1=Huang|first1=Tzuen-Luh|last2=Ruoff|first2=Arthur L.|bibcode=1984PhRvB..29.1112H}}

| LattConst_a = 0.4503 nm

| UnitCellFormulas = 1

| UnitCellVolume = 0.0913 nm³

| Coordination = Cubic (Cs⁺)
Cubic (I⁻)

}}

|Section5={{Chembox Thermochemistry

| DeltaHf = −346.6 kJ/molHaynes, p. 5.10

| Entropy = 123.1 J/mol·K

| DeltaGf = −340.6 kJ/mol

| HeatCapacity = 52.8 J/mol·K

}}

|Section7={{Chembox Hazards

| GHSSignalWord = Warning

| GHSPictograms = {{GHS07}}{{GHS08}}{{GHS09}}

| HPhrases = {{H-phrases|315|317|319|335}}

| PPhrases = {{P-phrases|201|202|261|264|270|271|272|273|280|281|301+312|302+352|304+340|305+351+338|308+313|312|321|330|332+313|333+313|337+313|362|363|391|403+233|405|501}}

| ExternalSDS =

| FlashPt = Non-flammable

| LD50 = 2386 mg/kg (oral, rat)

}}

|Section8={{Chembox Related

| OtherAnions = Caesium fluoride
Caesium chloride
Caesium bromide
Caesium astatide

| OtherCations = Lithium iodide
Sodium iodide
Potassium iodide
Rubidium iodide
Francium iodide

}}

Caesium iodide or cesium 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.{{cite journal|doi=10.1364/AO.25.002440|pmid=18231513|title=Quantum efficiency of cesium iodide photocathodes at soft x-ray and extreme ultraviolet wavelengths|journal=Applied Optics|volume=25|issue=14|pages=2440|year=1986|last1=Kowalski|first1=M. P.|last2=Fritz|first2=G. G.|last3=Cruddace|first3=R. G.|last4=Unzicker|first4=A. E.|last5=Swanson|first5=N.|bibcode=1986ApOpt..25.2440K}}

Synthesis and structure

File:CsX@DWNT.jpgs.{{cite journal|doi=10.1038/nmat4069|pmid=25218060|title=Atomic structure and dynamic behaviour of truly one-dimensional ionic chains inside carbon nanotubes|journal=Nature Materials|volume=13|issue=11|pages=1050–4|year=2014|last1=Senga|first1=Ryosuke|last2=Komsa|first2=Hannu-Pekka|last3=Liu|first3=Zheng|last4=Hirose-Takai|first4=Kaori|last5=Krasheninnikov|first5=Arkady V.|last6=Suenaga|first6=Kazu|bibcode=2014NatMa..13.1050S}}]]

Bulk caesium iodide crystals have the cubic CsCl crystal structure, but the structure type of nanometer-thin CsI films depends on the substrate material – it is CsCl for mica and NaCl for LiF, NaBr and NaCl substrates.{{cite journal|doi=10.1107/S0365110X51001641|title=Polymorphism of cesium and thallium halides|journal=Acta Crystallographica|volume=4|issue=6|pages=487–489|year=1951|last1=Schulz|first1=L. G.|bibcode=1951AcCry...4..487S }}

Caesium iodide atomic chains can be grown inside double-wall carbon nanotubes. In such chains I atoms appear brighter than Cs atoms in electron micrographs 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.

Properties

class="wikitable" style="text-align:center"

|+Solubility of Csl in waterHaynes, p. 5.191

!Т (°C)

!10

!20

!25

!30

!40

!50

!60

!70

!80

!90

!100

S (wt%)

|30.9

|37.2

|43.2

|45.9

|48.6

|53.3

|57.3

|60.7

|63.6

|65.9

|67.7

|69.2

Applications

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 low light yield that increases significantly with cooling,{{cite journal|title=Luminescence and scintillation properties of CsI: A potential cryogenic scintillator|journal=Physica Status Solidi B|volume=252|issue=4|pages=804–810|year=2015|last1=Mikhailik|first1=V.|last2=Kapustyanyk|first2=V.|last3=Tsybulskyi|first3=V.|last4=Rudyk|first4=V.|last5=Kraus|first5=H.|doi=10.1002/pssb.201451464|arxiv=1411.6246|bibcode=2015PSSBR.252..804M|s2cid=118668972}} and a fairly small Molière radius is 3.5 cm. It exhibits 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, working range into the far infrared. However, optical-quality CsI crystals are very soft and 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.{{cite book|author=Sun, Da-Wen |title=Infrared Spectroscopy for Food Quality Analysis and Control|url=https://books.google.com/books?id=bOWUDeiYshsC&pg=PA158|date=2009|publisher=Academic Press|isbn=978-0-08-092087-0|pages=158–}}

In addition to image intensifier input phosphors, caesium iodide is often also used in medicine as the scintillating material in flat panel x-ray detectors.{{cite book|last1=Lança|first1=Luís|last2=Silva|first2=Augusto|title=Digital Imaging Systems for Plain Radiography|date=2012|publisher=Springer|isbn=978-1-4614-5066-5|chapter-url=https://www.springer.com/cda/content/document/cda_downloaddocument/9781461450665-c1.pdf?SGWID=0-0-45-1368105-p174548440|chapter=Digital Radiography Detectors: A Technical Overview|doi=10.1007/978-1-4614-5067-2_2|hdl=10400.21/1932|access-date=2017-08-28|archive-date=2019-01-28|archive-url=https://web.archive.org/web/20190128083224/https://www.springer.com/cda/content/document/cda_downloaddocument/9781461450665-c1.pdf?SGWID=0-0-45-1368105-p174548440|url-status=dead}}

References

Cited sources

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Category:Caesium compounds

Category:Iodides

Category:Alkali metal iodides

Category:Metal halides

Category:Caesium chloride crystal structure