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Reflectron Ds
A reflectron (mass reflectron) is a type of time-of-flight mass spectrometer (TOF MS) that comprises a pulsed ion source, field-free region, ion mirror, and ion detector and uses a static or time dependent electric field in the ion mirror to reverse the direction of travel of the ions entering it. Using the reflectron, one can substantially diminish a spread of flight times of the ions with the same mass-to-charge ratio (''m/z'') caused by spread in kinetic energy of these ions measured at the exit from the ion source. Development The idea of improving mass resolution in TOF MS by implementing the reflection of ions from a region with retarding electric field (the ion mirror) has been first proposed by Russian scientist S. G. Alikhanov. In 1973, the dual-stage reflectron utilizing an ion mirror with two regions of homogeneous field was built in a laboratory of Boris Aleksandrovich Mamyrin. Mass resolution of the reflectron measured over broad mass range is much larger than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear
Linearity is the property of a mathematical relationship ('' function'') that can be graphically represented as a straight line. Linearity is closely related to '' proportionality''. Examples in physics include rectilinear motion, the linear relationship of voltage and current in an electrical conductor ( Ohm's law), and the relationship of mass and weight. By contrast, more complicated relationships are ''nonlinear''. Generalized for functions in more than one dimension, linearity means the property of a function of being compatible with addition and scaling, also known as the superposition principle. The word linear comes from Latin ''linearis'', "pertaining to or resembling a line". In mathematics In mathematics, a linear map or linear function ''f''(''x'') is a function that satisfies the two properties: * Additivity: . * Homogeneity of degree 1: for all α. These properties are known as the superposition principle. In this definition, ''x'' is not necessarily ... [...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 ionized, for example by bombarding it with a 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 (fragments) are then separated acco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circle
A circle is a shape consisting of all points in a plane that are at a given distance from a given point, the centre. Equivalently, it is the curve traced out by a point that moves in a plane so that its distance from a given point is constant. The distance between any point of the circle and the centre is called the radius. Usually, the radius is required to be a positive number. A circle with r=0 (a single point) is a degenerate case. This article is about circles in Euclidean geometry, and, in particular, the Euclidean plane, except where otherwise noted. Specifically, a circle is a simple closed curve that divides the plane into two regions: an interior and an exterior. In everyday use, the term "circle" may be used interchangeably to refer to either the boundary of the figure, or to the whole figure including its interior; in strict technical usage, the circle is only the boundary and the whole figure is called a '' disc''. A circle may also be defined as a special ki ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bruker
Bruker Corporation is an American manufacturer of scientific instruments for molecular and materials research, as well as for industrial and applied analysis. It is headquartered in Billerica, Massachusetts, and is the publicly traded parent company of Bruker Scientific Instruments (Bruker AXS, Bruker BioSpin, Bruker Daltonics and Bruker Optics) and Bruker Energy & Supercon Technologies (BEST) divisions. In April 2010, Bruker created a Chemical Analysis Division (headquartered in Fremont, CA) under the Bruker Daltonics subsidiary. This division contains three former Varian product lines: ICPMS systems, laboratory gas chromatography (GC), and GC- triple quadrupole mass spectrometer (originally designed by Bear Instruments and acquired by Varian in 2001). In 2012, it sponsored the Fritz Feigl Prize, and since 1999 the company has also sponsored the Günther Laukien Prize. History The company was founded on September 7, 1960, in Karlsruhe, Germany as ''Bruker-Physik AG'' by fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Einzel Lens
An einzel lens (from german: Einzellinse – single lens), or unipotential lens, is a charged particle electrostatic lens that focuses without changing the energy of the beam. It consists of three or more sets of cylindrical or rectangular apertures or tubes in series along an axis. It is used in ion optics to focus ions in flight, which is accomplished through manipulation of the electric field in the path of the ions. The electrostatic potential in the lens is symmetric, so the ions will regain their initial energy on exiting the lens, although the velocity of the outer particles will be altered such that they converge on to the axis. This causes the outer particles to arrive at the focus intersection slightly later than the ones that travel along a straight path, as they have to travel an extra distance. Theory The equation for the change in radial velocity for a particle as it passes between any pair of cylinders in the lens is: \Delta v_r = \int \frac dz, with ''z'' a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectron Ds
A reflectron (mass reflectron) is a type of time-of-flight mass spectrometer (TOF MS) that comprises a pulsed ion source, field-free region, ion mirror, and ion detector and uses a static or time dependent electric field in the ion mirror to reverse the direction of travel of the ions entering it. Using the reflectron, one can substantially diminish a spread of flight times of the ions with the same mass-to-charge ratio (''m/z'') caused by spread in kinetic energy of these ions measured at the exit from the ion source. Development The idea of improving mass resolution in TOF MS by implementing the reflection of ions from a region with retarding electric field (the ion mirror) has been first proposed by Russian scientist S. G. Alikhanov. In 1973, the dual-stage reflectron utilizing an ion mirror with two regions of homogeneous field was built in a laboratory of Boris Aleksandrovich Mamyrin. Mass resolution of the reflectron measured over broad mass range is much larger than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-linear
In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many other scientists because most systems are inherently nonlinear in nature. Nonlinear dynamical systems, describing changes in variables over time, may appear chaotic, unpredictable, or counterintuitive, contrasting with much simpler linear systems. Typically, the behavior of a nonlinear system is described in mathematics by a nonlinear system of equations, which is a set of simultaneous equations in which the unknowns (or the unknown functions in the case of differential equations) appear as variables of a polynomial of degree higher than one or in the argument of a function which is not a polynomial of degree one. In other words, in a nonlinear system of equations, the equation(s) to be solved cannot be written as a linear combination of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectron Ss
A reflectron (mass reflectron) is a type of time-of-flight mass spectrometer (TOF MS) that comprises a pulsed ion source, field-free region, ion mirror, and ion detector and uses a static or time dependent electric field in the ion mirror to reverse the direction of travel of the ions entering it. Using the reflectron, one can substantially diminish a spread of flight times of the ions with the same mass-to-charge ratio (''m/z'') caused by spread in kinetic energy of these ions measured at the exit from the ion source. Development The idea of improving mass resolution in TOF MS by implementing the reflection of ions from a region with retarding electric field (the ion mirror) has been first proposed by Russian scientist S. G. Alikhanov. In 1973, the dual-stage reflectron utilizing an ion mirror with two regions of homogeneous field was built in a laboratory of Boris Aleksandrovich Mamyrin. Mass resolution of the reflectron measured over broad mass range is much larger than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Time-of-flight Mass Spectrometer
Time-of-flight mass spectrometry (TOFMS) is a method of mass spectrometry in which an ion's mass-to-charge ratio is determined by a time of flight measurement. Ions are accelerated by an electric field of known strength. This acceleration results in an ion having the same kinetic energy as any other ion that has the same charge. The velocity of the ion depends on the mass-to-charge ratio (heavier ions of the same charge reach lower speeds, although ions with higher charge will also increase in velocity). The time that it subsequently takes for the ion to reach a detector at a known distance is measured. This time will depend on the velocity of the ion, and therefore is a measure of its mass-to-charge ratio. From this ratio and known experimental parameters, one can identify the ion. Theory The potential energy of a charged particle in an electric field is related to the charge of the particle and to the strength of the electric field: where ''E''p is potential energy, ''q'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metastable
In chemistry and physics, metastability denotes an intermediate energetic state within a dynamical system other than the system's state of least energy. A ball resting in a hollow on a slope is a simple example of metastability. If the ball is only slightly pushed, it will settle back into its hollow, but a stronger push may start the ball rolling down the slope. Bowling pins show similar metastability by either merely wobbling for a moment or tipping over completely. A common example of metastability in science is isomerisation. Higher energy isomers are long lived because they are prevented from rearranging to their preferred ground state by (possibly large) barriers in the potential energy. During a metastable state of finite lifetime, all state-describing parameters reach and hold stationary values. In isolation: *the state of least energy is the only one the system will inhabit for an indefinite length of time, until more external energy is added to the system (unique "ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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