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Iodine clock reaction
The iodine clock reaction, also known as the Landolt reaction, is a chemical kinetics demonstration where two colorless solutions mix and suddenly turn blue-black after a predictable delay.
Iodine monochloride
Iodine monochloride (ICl) is an interhalogen compound of iodine and chlorine that exists as black crystals or a reddish brown oily liquid and is the active component of Wijs solution.
Iodine value
The iodine value, or iodine number, is the mass of iodine absorbed by 100 grams of a fat or oil, measuring the unsaturation of its fatty acids.
Iodine-123
Iodine-123 is a radioactive isotope of iodine, decaying with a 13.2-hour half-life and a 159 keV gamma ray suited to SPECT imaging; it is used for thyroid studies and has largely replaced iodine-131 for diagnostics.
Iodine-125
Iodine-125 (¹²⁵I) is a radioactive isotope of iodine with a half-life of 59.4 days that decays by electron capture, used mainly in permanent-seed brachytherapy for localized prostate cancer.
Iodine-129
Iodine-129 is a long-lived radioactive isotope of iodine with a half-life of 15.7 million years, produced by cosmic rays and nuclear reactors, and used as an environmental tracer.
Iodine-131
Iodine-131 is a radioactive isotope of iodine with a half-life of about 8 days, used medically to treat hyperthyroidism and thyroid cancer and produced as a fission product.
Iodine-based optical clock
An iodine-based optical clock is an optical atomic clock whose laser is stabilized to a narrow absorption line of molecular iodine, making it simpler and more portable than ion or lattice clocks.
Iodixanol
Iodixanol, marketed as Visipaque, is a non-ionic dimeric iodinated X-ray contrast medium formulated to be iso-osmolar with blood, used in coronary and cerebral angiography and CT.
Iodoform
Iodoform, also known as triiodomethane or methyl triiodide, is a yellow crystalline organoiodine compound (CHI3) used historically as a wound antiseptic and in the iodoform test for methyl ketones.
Iodometry
Iodometry, or iodometric titration, is an indirect redox titration method in which an oxidizing analyte liberates iodine, titrated with sodium thiosulfate to a starch endpoint.
Iodophenol
Iodophenol is any of the three monohydroxy monoiodinated derivatives of phenol, 2-, 3-, and 4-iodophenol, each with formula C₆H₅IO; the motif appears in thyroid hormones and X-ray contrast-agent intermediates.
Ioel Malkin
Ioel Malkin (Иоэль Малкин) was a Soviet mathematician who extended Lyapunov's second method with converse stability theorems, founded the Ural school of stability of motion, and taught Nikolay Krasovsky.
Ioffe Institute
The Ioffe Institute, or Ioffe Physical-Technical Institute (Физико-технический институт им. А.Ф. Иоффе), is a Russian physics research institute in St Petersburg founded in 1918 by Abram Ioffe.
Iohexol
Iohexol is a non-ionic, low-osmolar iodinated X-ray contrast medium sold as Omnipaque by GE Healthcare, used in imaging and to measure kidney function, first US approved in 1985.
Iomeprol
Iomeprol, marketed as Iomeron in Europe and Iomervu in the United States since 2024, is a non-ionic low-osmolar iodinated contrast medium by Bracco used in CT and angiography.
Ion
An ion is an atomic or molecular particle with a net electric charge: a cation forms when an atom loses electrons, and an anion forms when it gains electrons.
Ion acoustic wave
The ion acoustic wave, or ion sound wave, is a low-frequency electrostatic wave in a plasma, analogous to a sound wave in an ordinary gas.
Ion beam analysis
Ion beam analysis is a group of analytical techniques in which a beam of MeV ions strikes a material, and emitted X-rays, gamma rays, or scattered particles reveal its composition.
Ion beam scanning electron microscopy
Ion beam scanning electron microscopy (FIB-SEM) is a dual-beam technique in which a focused ion beam mills a specimen while a co-mounted electron column images it.
Ion chromatography
Ion chromatography (IC), also known as ion-exchange chromatography, is a liquid chromatography technique for separating ions, introduced by Hamish Small at Dow Chemical in 1975.
Ion counting
Ion counting is a mass spectrometry detection method that registers individual ions arriving at a detector, quantifying isotope abundances from count rates for very small ion beams.
Ion cyclotron resonance
Ion cyclotron resonance (ICR) is the resonant absorption of energy by an ion in a static magnetic field when an applied radiofrequency electric field matches the ion's cyclotron frequency.
Ion cyclotron resonance heating
Ion cyclotron resonance heating, also called ICRF heating, heats fusion plasma by launching radio waves that ions absorb at their cyclotron resonance, at 20 to 100 MHz.
Ion exchange
Ion exchange is a reversible chemical process that swaps ions held on a solid resin for ions of the same charge in a liquid, used in water softening and chromatography.
Ion exchange synthesis
Ion exchange synthesis is a post-synthetic method that swaps the ions of a preformed solid for ions from solution, molten salt, or gas, often preserving the crystal framework.
Ion flotation
Ion flotation is an adsorptive bubble separation method that removes dilute ions from aqueous solution by binding them to oppositely charged surfactant collectors floated to the surface with gas bubbles.
Ion gel
An ion gel, also called an ionogel, is a soft polymer gel swollen with an ionic liquid, combining high ionic conductivity with solid-like mechanical stability.
Ion microbeam analysis
Ion microbeam analysis measures elemental, isotopic, or structural properties of a small sample region by scanning a focused megaelectronvolt ion beam and detecting the resulting signals.
Ion microscopy
Ion microscopy is a family of imaging techniques that scans a focused ion beam across a sample, building images from secondary electrons or ions with sub-nanometer resolution.