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.[9]
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.[8]
Properties
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.[11] 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, 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.[12]
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.[13]
References
Wikimedia Commons has media related to Caesium iodide.
^ a bCesium iodide. U.S. National Library of Medicine
^ a b c d eHaynes, p. 4.57
^Haynes, p. 4.132
^Haynes, p. 10.240
^Huang, Tzuen-Luh; Ruoff, Arthur L. (1984). "Equation of state and high-pressure phase transition of CsI". Physical Review B. 29 (2): 1112. Bibcode:1984PhRvB..29.1112H. doi:10.1103/PhysRevB.29.1112.
^ a b c dHaynes, p. 5.10
^Kowalski, M. P.; Fritz, G. G.; Cruddace, R. G.; Unzicker, A. E.; Swanson, N. (1986). "Quantum efficiency of cesium iodide photocathodes at soft x-ray and extreme ultraviolet wavelengths". Applied Optics. 25 (14): 2440. Bibcode:1986ApOpt..25.2440K. doi:10.1364/AO.25.002440. PMID 18231513.
^Schulz, L. G. (1951). "Polymorphism of cesium and thallium halides". Acta Crystallographica. 4 (6): 487–489. Bibcode:1951AcCry...4..487S. doi:10.1107/S0365110X51001641.
^Haynes, p. 5.191
^Mikhailik, V.; Kapustyanyk, V.; Tsybulskyi, V.; Rudyk, V.; Kraus, H. (2015). "Luminescence and scintillation properties of CsI: A potential cryogenic scintillator". Physica Status Solidi B. 252 (4): 804–810. arXiv:1411.6246. Bibcode:2015PSSBR.252..804M. doi:10.1002/pssb.201451464. S2CID 118668972.
^Sun, Da-Wen (2009). Infrared Spectroscopy for Food Quality Analysis and Control. Academic Press. pp. 158–. ISBN 978-0-08-092087-0.
^Lança, Luís; Silva, Augusto (2012). "Digital Radiography Detectors: A Technical Overview" (PDF). Digital Imaging Systems for Plain Radiography. Springer. doi:10.1007/978-1-4614-5067-2_2. hdl:10400.21/1932. ISBN 978-1-4614-5066-5. Archived from the original (PDF) on 2019-01-28. Retrieved 2017-08-28.
