Arthur Jeffrey Dempster

Uranium-235 is an isotope of uranium that differs from the element's other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction, i.e., it is fissile. In fact, U-235 is the only fissile isotope found in nature. It was discovered in 1935 by Arthur Jeffrey Dempster. A uranium nucleus that absorbs a neutron splits into two lighter nuclei; this is called nuclear fission. It releases either two or three neutrons which continue the reaction. In nuclear reactors, the reaction is slowed down by the ad ...

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Mass spectrometry - Ion source. The ion source is the part of the mass spectrometer that ionizes the material under analysis (the analyte). The ions are then transported by magnetic or electrical fields to the mass analyzer. Techniques for ionization have been key to determining what types of samples can be analyzed by mass spectrometry. Electron ionization and chemical ionization are used for gases and vapors. In chemical ionization sources, the analyte is ionized by chemical ion-molecule reactions during ...

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Mass spectrometry, Mass spectrometry - How it works in layman terms, Mass spectrometry - Instrumentation, Mass spectrometry - Ion source, Mass spectrometry - Mass analyzer, Mass spectrometry - Detector, Mass spectrometry - Hyphenated MS, Mass spectrometry - Gas chromatography/MS, Mass spectrometry - Liquid chromatography/MS, Mass spectrometry - IMS/MS, Mass spectrometry - Tandem MS MS/MS, Mass spectrometry - Applications, Mass spectrometry - Isotope ratio MS, Mass spectrometry - Trace Gas Analysis, Mass spectrometry - Pharmcokinetics, Mass spectrometry - Mass spectrometry of proteins, Mass spectrometry - Protein and peptide fractionation coupled with mass spectrometry, Mass spectrometry - Protein identification, Mass spectrometry - History

Read more here: » Mass spectrometry: Encyclopedia II - Mass spectrometry - Instrumentation

Mass spectrometry - Isotope ratio MS. Mass spectrometry is also used to determine the isotopic composition of elements within a sample. Differences in mass among isotopes of an element are very small, and the less abundant isotopes of an element are typically very rare, so a very sensitive instrument is required. These instruments, sometimes referred to as isotope ratio mass spectrometers (IR-MS), usually use a single magnet to bend a beam of ionized particles towards a series of Faraday cups which convert partic ...

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Mass spectrometry, Mass spectrometry - How it works in layman terms, Mass spectrometry - Instrumentation, Mass spectrometry - Ion source, Mass spectrometry - Mass analyzer, Mass spectrometry - Detector, Mass spectrometry - Hyphenated MS, Mass spectrometry - Gas chromatography/MS, Mass spectrometry - Liquid chromatography/MS, Mass spectrometry - IMS/MS, Mass spectrometry - Tandem MS MS/MS, Mass spectrometry - Applications, Mass spectrometry - Isotope ratio MS, Mass spectrometry - Trace Gas Analysis, Mass spectrometry - Pharmcokinetics, Mass spectrometry - Mass spectrometry of proteins, Mass spectrometry - Protein and peptide fractionation coupled with mass spectrometry, Mass spectrometry - Protein identification, Mass spectrometry - History

Read more here: » Mass spectrometry: Encyclopedia II - Mass spectrometry - Applications

Mass spectrometry - Gas chromatography/MS. See also the main article on Gas chromatography-mass spectrometry A common form of mass spectrometry is gas chromatography-mass spectrometry (GC/MS or GC-MS). In this technique, a gas chromatograph is used to separate compounds. This stream of separated compounds is fed on-line into the ion source, a metallic filament to which voltage is applied. This filament emits electrons which ionize the compounds. The ions can then further fragment, yielding predictable patterns. Intact ions and fragments pass into the mass s ...

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Mass spectrometry, Mass spectrometry - How it works in layman terms, Mass spectrometry - Instrumentation, Mass spectrometry - Ion source, Mass spectrometry - Mass analyzer, Mass spectrometry - Detector, Mass spectrometry - Hyphenated MS, Mass spectrometry - Gas chromatography/MS, Mass spectrometry - Liquid chromatography/MS, Mass spectrometry - IMS/MS, Mass spectrometry - Tandem MS MS/MS, Mass spectrometry - Applications, Mass spectrometry - Isotope ratio MS, Mass spectrometry - Trace Gas Analysis, Mass spectrometry - Pharmcokinetics, Mass spectrometry - Mass spectrometry of proteins, Mass spectrometry - Protein and peptide fractionation coupled with mass spectrometry, Mass spectrometry - Protein identification, Mass spectrometry - History

Read more here: » Mass spectrometry: Encyclopedia II - Mass spectrometry - Hyphenated MS

Different molecules have different masses, and this fact is used in a mass spectrometer to determine what molecules are present in a sample. For example, table salt (NaCl), is vaporized (turned into gas) and broken down (ionized) into electrically charged particles, called ions, in the first part of the mass spectrometer. The sodium ions and chloride ions have specific molecular weights. They also have a charge, which means that they will be moved under the influence of an electric field. These ions are then sent into an ion acceleration cha ...

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Mass spectrometry, Mass spectrometry - How it works in layman terms, Mass spectrometry - Instrumentation, Mass spectrometry - Ion source, Mass spectrometry - Mass analyzer, Mass spectrometry - Detector, Mass spectrometry - Hyphenated MS, Mass spectrometry - Gas chromatography/MS, Mass spectrometry - Liquid chromatography/MS, Mass spectrometry - IMS/MS, Mass spectrometry - Tandem MS MS/MS, Mass spectrometry - Applications, Mass spectrometry - Isotope ratio MS, Mass spectrometry - Trace Gas Analysis, Mass spectrometry - Pharmacokinetics, Mass spectrometry - Mass spectrometry of proteins, Mass spectrometry - Protein and peptide fractionation coupled with mass spectrometry, Mass spectrometry - Protein identification, Mass spectrometry - History

Read more here: » Mass spectrometry: Encyclopedia II - Mass spectrometry - How it works in layman terms

The first mass spectrography technique was described in an 1899 article by English scientist J.J. Thomson. The processes that more directly gave rise to the modern version were devised by Arthur Jeffrey Dempster and F.W. Aston in 1918 and 1919 respectively. In 2002, the Nobel Prize in Chemistry was received by John Fenn for the development of electrospray ionization (ESI) and Koichi Tanaka for the development of soft laser desorption (SLD) in 1987. An improved SLD method, matrix-assisted laser desorption/ionization (MALDI), was develo ...

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Mass spectrometry, Mass spectrometry - How it works in layman terms, Mass spectrometry - Instrumentation, Mass spectrometry - Ion source, Mass spectrometry - Mass analyzer, Mass spectrometry - Detector, Mass spectrometry - Hyphenated MS, Mass spectrometry - Gas chromatography/MS, Mass spectrometry - Liquid chromatography/MS, Mass spectrometry - IMS/MS, Mass spectrometry - Tandem MS MS/MS, Mass spectrometry - Applications, Mass spectrometry - Isotope ratio MS, Mass spectrometry - Trace Gas Analysis, Mass spectrometry - Pharmcokinetics, Mass spectrometry - Mass spectrometry of proteins, Mass spectrometry - Protein and peptide fractionation coupled with mass spectrometry, Mass spectrometry - Protein identification, Mass spectrometry - History

Read more here: » Mass spectrometry: Encyclopedia II - Mass spectrometry - History

Different molecules have different masses, and this fact is used in a mass spectrometer to determine what molecules are present in a sample. For example, table salt (NaCl), is vaporized (turned into gas) and broken down (ionized) into electrically charged particles, called ions, in the first part of the mass spectometer. The sodium ions and chloride ions have specific molecular weights. They also have a charge, which means that they will be moved under the influence of an electric field. These ions are then sent into an ion acceleration cham ...

See also:

Mass spectrometry, Mass spectrometry - How it works in layman terms, Mass spectrometry - Instrumentation, Mass spectrometry - Ion source, Mass spectrometry - Mass analyzer, Mass spectrometry - Detector, Mass spectrometry - Hyphenated MS, Mass spectrometry - Gas chromatography/MS, Mass spectrometry - Liquid chromatography/MS, Mass spectrometry - IMS/MS, Mass spectrometry - Tandem MS MS/MS, Mass spectrometry - Applications, Mass spectrometry - Isotope ratio MS, Mass spectrometry - Trace Gas Analysis, Mass spectrometry - Pharmcokinetics, Mass spectrometry - Mass spectrometry of proteins, Mass spectrometry - Protein and peptide fractionation coupled with mass spectrometry, Mass spectrometry - Protein identification, Mass spectrometry - History

Read more here: » Mass spectrometry: Encyclopedia II - Mass spectrometry - How it works in layman terms