caesium frequency


The development of the cesium (Cs) frequency standard took place at the same time as the discussion and adoption of the Ephemeris second. Caesium-137 is a radioisotope commonly used as a gamma-emitter in industrial applications. Friestad, Gregory K.; Branchaud, Bruce P.; Navarrini, Walter and Sansotera, Maurizio (2007) "Cesium Fluoride" in, General Conference on Weights and Measures, International Union of Pure and Applied Chemistry, "Atomic weights of the elements 2013 (IUPAC Technical Report)", "NIST Radionuclide Half-Life Measurements", "History of the recommended atomic-weight values from 1882 to 1997: a comparison of differences from current values to the estimated uncertainties of earlier values", "C&EN: It's Elemental: The Periodic Table – Cesium", "Density of melts of alkali metals and their Na-K-Cs and Na-K-Rb ternary systems", "A Basic Rule of Chemistry Can Be Broken, Calculations Show", "Effects of relativistic motion of electrons on the chemistry of gold and platinum", "Single-atom electron energy loss spectroscopy of light elements", "The Crystal Structure of Cesium Monoxide", "Nucleosynthesis in Asymptotic Giant Branch Stars: Relevance for Galactic Enrichment and Solar System Formation", IEER Report: Transmutation – Nuclear Alchemy Gamble, Chernobyl's Legacy: Health, Environmental and Socia-Economic Impacts and Recommendations to the Governments of Belarus, Russian Federation and Ukraine, "Transmutation of Cesium-137 Using Proton Accelerator", "Distribution of the elements in some major units of the Earth's crust", 10.1130/0016-7606(1961)72[175:DOTEIS]2.0.CO;2, "Cesium as a Raw Material: Occurrence and Uses", "The Tanco Pegmatite at Bernic Lake, Manitoba: X. Pollucite", "Lithium, cesium, and rubidium—The rare alkali metals", "Cesium formate fluid succeeds in North Sea HPHT field trials", "Chemische Analyse durch Spectralbeobachtungen", "Ueber die Darstellung von Rubidium- und Cäsiumverbindungen und über die Gewinnung der Metalle selbst", "Cesium Supplier & Technical Information", "The material flow of radioactive cesium-137 in the U.S. 2000", "IsoRay's Cesium-131 Medical Isotope Used In Milestone Procedure Treating Eye Cancers At Tufts-New England Medical Center", "Level and density measurement using non-contact nuclear gauges", "Isotope Tracers Project – Resources on Isotopes – Cesium", "A Synopsis of Ion Propulsion Development Projects in the United States: SERT I to Deep Space I", "Infrared illumination compositions and articles containing the same", "Accumulation of potassium, rubidium and caesium (, "IAEA director warns of 'dirty bomb' risk", View the reaction of Caesium (most reactive metal in the periodic table) with Fluorine (most reactive non-metal), https://en.wikipedia.org/w/index.php?title=Caesium&oldid=982889163, Wikipedia pages semi-protected against vandalism, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License, This page was last edited on 11 October 2020, at 00:19.
Products | Applications | Company | Careers | Investors | Survey | Privacy Policy | Terms & Conditions | Product Disclaimer | Terms of Use | Blog |. After reduction of the hexachloroplatinate with hydrogen, caesium and rubidium were separated by the difference in solubility of their carbonates in alcohol. [99], Caesium nitrate is used as an oxidizer and pyrotechnic colorant to burn silicon in infrared flares,[100] such as the LUU-19 flare,[101] because it emits much of its light in the near infrared spectrum. Caesium Clock Cs4000 Cesium Frequency Standard. [11], The metal can also be isolated by electrolysis of fused caesium cyanide (CsCN). [73], Caesium metal is one of the most reactive elements and is highly explosive in the presence of water. [84] Other uses of the metal include high-energy lasers, vapour glow lamps, and vapour rectifiers. [11], It is highly pyrophoric: the autoignition temperature of caesium is −116 °C (−177 °F), and it ignites explosively in air to form caesium hydroxide and various oxides. When a cesium atom receives microwave … Eventually, a microwave frequency is found that alters the states of most of the cesium atoms and maximizes their fluorescence. [78], Caesium is also important for its photoemissive properties, converting light to electron flow. This frequency is the natural resonance frequency of the cesium atom (9,192,631,770 Hz), or the frequency used to define the second. The combination of laser cooling and the fountain design allows NIST-F1 to observe cesium atoms for longer periods, and thus achieve its unprecedented accuracy. The photons, or the tiny packets of light that they emit, are measured by a detector. The largest present-day use of nonradioactive caesium is in caesium formate drilling fluids for the extractive oil industry. This was done by Markowitz in 1958. About 10% of absorbed radiocaesium washes out of the body relatively quickly in sweat and urine.

[106], Nonradioactive caesium compounds are only mildly toxic, and nonradioactive caesium is not a significant environmental hazard. During the trip, the atomic states of the atoms might or might not be altered as they interact with the microwave signal.

It is used in photoelectric cells because caesium-based cathodes, such as the intermetallic compound K2CsSb, have a low threshold voltage for emission of electrons.
Our Cesium instruments are built to provide stand-alone dependability, ease of use, and ease of installation. [97][98] Nevertheless, field-emission electric propulsion thrusters that accelerate liquid metal ions such as caesium have been built. 1.544 MHz and composite outputs, Up to ±1e-12 frequency stability over temperature. [72] The 13th General Conference on Weights and Measures of 1967 defined a second as: "the duration of 9,192,631,770 cycles of microwave light absorbed or emitted by the hyperfine transition of caesium-133 atoms in their ground state undisturbed by external fields". This is achieved under full environmental conditions in 30 minutes or less- and without the need for any adjustments or alignments. It is defined by taking the fixed numerical value of the caesium frequency Cs, the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s–1. Caesium fluoride enjoys a niche use in organic chemistry as a base[23] and as an anhydrous source of fluoride ion. [71] Applications for nonradioactive caesium included photoelectric cells, photomultiplier tubes, optical components of infrared spectrophotometers, catalysts for several organic reactions, crystals for scintillation counters, and in magnetohydrodynamic power generators. Being a heavy element, caesium provides good stopping power with better detection.

The range of the microwave generator is already close to this exact frequency, as it comes from an accurate crystal oscillator. Traditional cesium clocks measure room-temperature atoms moving at several hundred meters per second. [117][118] Experiments with dogs showed that a single dose of 3.8 millicuries (140 MBq, 4.1 μg of caesium-137) per kilogram is lethal within three weeks;[119] smaller amounts may cause infertility and cancer. Because of the bright blue lines in the emission spectrum, they derived the name from the Latin word caesius, meaning sky-blue. [111] The principal use of nonradioactive caesium is as caesium formate in petroleum drilling fluids because it is much less toxic than alternatives, though it is more costly.

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