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Thomson (unit)
The thomson (symbol: Th) is a unit that has appeared infrequently in scientific literature relating to the field of mass spectrometry as a unit of mass-to-charge ratio. The unit was proposed by R. Graham Cooks and Alan L. Rockwood naming it in honour of J. J. Thomson who measured the mass-to-charge ratio of electrons and ions. Definition The thomson is defined as : 1~\mathrm = 1~\frac \approx 1.036426 \times 10^\,\mathrm where Da is the symbol for the unit dalton (also called the unified atomic mass unit, symbol u), and ''e'' is the elementary charge, which is the unit of electric charge in the system of atomic units. For example, the ion C7H72+ has a mass of 91 Da. Its charge number is +2, and hence its charge is 2''e''. The ion will be observed at 45.5 Th in a mass spectrum. The thomson allows for negative values for negatively charged ions. For example, the benzoate anion would be observed at −121 Th since the charge is −''e''. Use The thomson has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass-to-charge Ratio
The mass-to-charge ratio (''m''/''Q'') is a physical quantity Ratio, relating the ''mass'' (quantity of matter) and the ''electric charge'' of a given particle, expressed in Physical unit, units of kilograms per coulomb (kg/C). It is most widely used in the electrodynamics of charged particles, e.g. in electron optics and ion optics. It appears in the scientific fields of electron microscopy, cathode ray tubes, accelerator physics, nuclear physics, Auger electron spectroscopy, physical cosmology, cosmology and mass spectrometry. The importance of the mass-to-charge ratio, according to classical electrodynamics, is that two particles with the same mass-to-charge ratio move in the same path in a vacuum, when subjected to the same electric and magnetic fields. Some disciplines use the charge-to-mass ratio (''Q''/''m'') instead, which is the multiplicative inverse of the mass-to-charge ratio. The CODATA recommended value for an electron is Origin When charged particles move in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a type of plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds. In a typical MS procedure, a sample, which may be solid, liquid, or gaseous, is ionization, ionized, for example by bombarding it with a Electron ionization, beam of electrons. This may cause some of the sample's molecules to break up into positively charged fragments or simply become positively charged without fragmenting. These ions (fragmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass-to-charge Ratio
The mass-to-charge ratio (''m''/''Q'') is a physical quantity Ratio, relating the ''mass'' (quantity of matter) and the ''electric charge'' of a given particle, expressed in Physical unit, units of kilograms per coulomb (kg/C). It is most widely used in the electrodynamics of charged particles, e.g. in electron optics and ion optics. It appears in the scientific fields of electron microscopy, cathode ray tubes, accelerator physics, nuclear physics, Auger electron spectroscopy, physical cosmology, cosmology and mass spectrometry. The importance of the mass-to-charge ratio, according to classical electrodynamics, is that two particles with the same mass-to-charge ratio move in the same path in a vacuum, when subjected to the same electric and magnetic fields. Some disciplines use the charge-to-mass ratio (''Q''/''m'') instead, which is the multiplicative inverse of the mass-to-charge ratio. The CODATA recommended value for an electron is Origin When charged particles move in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alan L
Alan may refer to: People *Alan (surname), an English and Kurdish surname *Alan (given name), an English given name ** List of people with given name Alan ''Following are people commonly referred to solely by "Alan" or by a homonymous name.'' * Alan (Chinese singer) (born 1987), female Chinese singer of Tibetan ethnicity, active in both China and Japan * Alan (Mexican singer) (born 1973), Mexican singer and actor *Alan (wrestler) (born 1975), a.k.a. Gato Eveready, who wrestles in Asistencia Asesoría y Administración * Alan (footballer, born 1979) (Alan Osório da Costa Silva), Brazilian footballer * Alan (footballer, born 1998) (Alan Cardoso de Andrade), Brazilian footballer *Alan I, King of Brittany (died 907), "the Great" * Alan II, Duke of Brittany (c. 900–952) * Alan III, Duke of Brittany(997–1040) * Alan IV, Duke of Brittany (c. 1063–1119), a.k.a. Alan Fergant ("the Younger" in Breton language) * Alan of Tewkesbury, 12th century abbott * Alan of Lynn (c. 1348–1423), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rapid Communications In Mass Spectrometry
''Rapid Communications in Mass Spectrometry'' (''RCM'') is a biweekly peer-reviewed scientific journal published since 1987 by John Wiley & Sons. It covers research on all aspects of mass spectrometry. According to the ''Journal Citation Reports'', the journal has a 2020 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious or important within their field. The Impact Factor of a journa ... of 2.419. RCM Beynon Prize To mark the 80th birthday of John H. Beynon, the founding Editor of RCM, in 2004 an annual award was established in his honour by the publishers. The award is made on the recommendation of an ad hoc Sub-committee of the editorial board of RCM. References External links * Mass spectrometry journals Academic journals established in 1987 Wiley (publisher) academic journals {{biochem-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dalton (unit)
The dalton or unified atomic mass unit (symbols: Da or u, respectively) is a unit of mass defined as of the mass of an Bound state, unbound neutral atom of carbon-12 in its nuclear and electronic ground state and invariant mass, at rest. It is a Non-SI units mentioned in the SI, non-SI unit accepted for use with SI. The word "unified" emphasizes that the definition was accepted by both IUPAP and IUPAC. The atomic mass constant, denoted , is defined identically. Expressed in terms of , the atomic mass of carbon-12: . Its value in International System of Units, SI units is an experimentally determined quantity. The 2022 CODATA recommended value of the atomic mass constant expressed in the SI base unit kilogram is:This value serves as a Conversion of units, conversion factor of mass from daltons to kilograms, which can easily be converted to Gram, grams and other metric units of mass. The 2019 revision of the SI redefined the kilogram by fixing the value of the Planck constant (), i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elementary Charge
The elementary charge, usually denoted by , is a fundamental physical constant, defined as the electric charge carried by a single proton (+1 ''e'') or, equivalently, the magnitude of the negative electric charge carried by a single electron, which has charge −1 . In SI units, the coulomb is defined such that the value of the elementary charge is exactly or 160.2176634 zeptocoulombs (zC). Since the 2019 revision of the SI, the seven SI base units are defined in terms of seven fundamental physical constants, of which the elementary charge is one. In the centimetre–gram–second system of units (CGS), the corresponding quantity is . Robert A. Millikan and Harvey Fletcher's oil drop experiment first directly measured the magnitude of the elementary charge in 1909, differing from the modern accepted value by just 0.6%. Under assumptions of the then-disputed atomic theory, the elementary charge had also been indirectly inferred to ~3% accuracy from blackb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Units Of Measurement
A unit of measurement, or unit of measure, is a definite magnitude (mathematics), magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multiple of the unit of measurement. For example, a length is a physical quantity. The metre (symbol m) is a unit of length that represents a definite predetermined length. For instance, when referencing "10 metres" (or 10 m), what is actually meant is 10 times the definite predetermined length called "metre". The definition, agreement, and practical use of units of measurement have played a crucial role in human endeavour from early ages up to the present. A multitude of System of measurement, systems of units used to be very common. Now there is a global standard, the International System of Units (SI), the modern form of the metric system. In trade, weights and measures are often a su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Charge
Electric charge (symbol ''q'', sometimes ''Q'') is a physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative''. Like charges repel each other and unlike charges attract each other. An object with no net charge is referred to as neutral particle, electrically neutral. Early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that do not require consideration of quantum mechanics, quantum effects. In an isolated system, the total charge stays the same - the amount of positive charge minus the amount of negative charge does not change over time. Electric charge is carried by subatomic particles. In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the atomic nucleus, nuclei of atoms. If there are more electrons than protons in a piece of matter, it will have a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Units
The atomic units are a system of natural units of measurement that is especially convenient for calculations in atomic physics and related scientific fields, such as computational chemistry and atomic spectroscopy. They were originally suggested and named by the physicist Douglas Hartree. Atomic units are often abbreviated "a.u." or "au", not to be confused with similar abbreviations used for astronomical units, arbitrary units, and absorbance units in other contexts. Motivation In the context of atomic physics, using the atomic units system can be a convenient shortcut, eliminating symbols and numbers and reducing the order of magnitude of most numbers involved. For example, the Hamiltonian operator in the Schrödinger equation for the helium atom with standard quantities, such as when using SI units, is : \hat = - \frac \nabla_1^2 - \frac \nabla_2^2 - \frac - \frac + \frac , but adopting the convention associated with atomic units that transforms quantities into dimensionl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzoate
Benzoic acid () is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. The benzoyl group is often abbreviated "Bz" (not to be confused with "Bn," which is used for benzyl), thus benzoic acid is also denoted as BzOH, since the benzoyl group has the formula –. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only source. Benzoic acid occurs naturally in many plants and serves as an intermediate in the biosynthesis of many secondary metabolites. Salts of benzoic acid are used as food preservatives. Benzoic acid is an important precursor for the industrial synthesis of many other organic substances. The salts and esters of benzoic acid are known as benzoates (). History Benzoic acid was discovered in the sixteenth century. The dry distillation of gum benzoin was first described by Nostradamus (1556), and then by Ale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Alexeyevich Makarov
Alexander Alexeyevich Makarov, (; born 1966) is a Russian physicist who led the team that developed the Orbitrap, a type of mass spectrometer, and received the 2008 American Society for Mass Spectrometry Distinguished Contribution in Mass Spectrometry Award for this development. In November 2013 he was appointed to Professor by Special Appointment of High Resolution Mass Spectrometry at the Department of Chemistry and the Bijvoet Center for Biomolecular Research of Utrecht University in the Netherlands. As of 2016, he is Director of Global Research for Life Sciences Mass Spectrometry at Thermo Fisher Scientific. Early life and education * 1989 Moscow Engineering Physics Institute - M.S. Molecular Physics * 1993 Moscow Engineering Physics Institute - Ph.D. Physics and Mathematics * 1994-1996 Warwick University - Postdoctoral Appointment Awards * 2008 ASMS Distinguished Contribution in Mass Spectrometry Award * 2012 Thomson Medal Award * 2020 Fellow of the Royal Society ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
