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Reflectron
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 th ... [...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] |
Reflectron
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 th ... [...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 tha ... [...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 tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflectron Schematic
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 tha ... [...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 accordin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boris Aleksandrovich Mamyrin
Boris Aleksandrovich Mamyrin (russian: Борис Александрович Мамырин; 25 May 1919 5 March 2007) was a Soviet scientist best known for his invention of the electrostatic ion mirror mass spectrometer known as the reflectron. Biography Mamyrin was born in 1919 in Lipetsk, Soviet Russia during Russian civil war. Both of his parents were medical doctors and his early aim was to follow in their footsteps. However, shortly after he obtained his M.S. degree in physics from the Leningrad Polytechnic Institute, World War II cut his studies short. He served in the army throughout the war, finally discharging from military service in 1948. He returned to the Polytechnic Institute and obtained his doctoral degree within a year. He was the head and leading research scientist of the laboratory for mass spectrometry at Ioffe Physico-Technical Institute of the Russian Academy of Sciences. He was a corresponding member of the Russian Academy of Sciences and a full member of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soviet Inventions
This timeline of Russian Innovation encompasses key events in the history of technology in Russia, from the Grand Duchy of Moscow up to the Russian Federation. The entries in this timeline fall into the following categories: * indigenous inventions, like airliners, AC transformers, radio receivers, television, artificial satellites, ICBMs * uniquely Russian products, objects and events, like Saint Basil's Cathedral, Matryoshka dolls, Russian vodka * products and objects with superlative characteristics, like the Tsar Bomba, the AK-47, and the Typhoon-class submarine * scientific and medical discoveries, like the periodic law, vitamins and stem cells This timeline includes scientific and medical discoveries, products and technologies introduced by various peoples of Russia and its predecessor states, regardless of ethnicity, and also lists inventions by naturalized immigrant citizens. Certain innovations achieved internationally may also appear in this timeline in cases wher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Resolution
In mass spectrometry, resolution is a measure of the ability to distinguish two peaks of slightly different mass-to-charge ratios ''ΔM'', in a mass spectrum. Resolution and resolving power There are two different definitions of resolution and resolving power in mass spectrometry. IUPAC definition The IUPAC definition for resolution in mass spectrometry is :R = \cfrac = \mathrm :\Delta M = \mathrm :M = \mathrm Where a larger resolution indicates a better separation of peaks. This definition is used in a number of mass spectrometry texts. This use is also implied by the term "high-resolution mass spectrometry." A high value for resolution corresponding to good separation of peaks is similar to the convention used with chromatography separations, although it is important to note that the definitions are not the same. High resolution indicating better peak separation is also used in ion mobility spectrometry. Resolving power definition Some mass spectrometrists use the definit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dalton (unit)
The dalton or unified atomic mass unit (symbols: Da or u) is a non-SI unit of mass widely used in physics and chemistry. It is defined as of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. The atomic mass constant, denoted ''m''u, is defined identically, giving . This unit is commonly used in physics and chemistry to express the mass of atomic-scale objects, such as atoms, molecules, and elementary particles, both for discrete instances and multiple types of ensemble averages. For example, an atom of helium-4 has a mass of . This is an intrinsic property of the isotope and all helium-4 atoms have the same mass. Acetylsalicylic acid (aspirin), , has an average mass of approximately . However, there are no acetylsalicylic acid molecules with this mass. The two most common masses of individual acetylsalicylic acid molecules are , having the most common isotopes, and , in which one carbon is carbon-13. The molecular mass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matrix-assisted Laser Desorption/ionization
In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy absorbing matrix to create ions from large molecules with minimal fragmentation. It has been applied to the analysis of biomolecules ( biopolymers such as DNA, proteins, peptides and carbohydrates) and various organic molecules (such as polymers, dendrimers and other macromolecules), which tend to be fragile and fragment when ionized by more conventional ionization methods. It is similar in character to electrospray ionization (ESI) in that both techniques are relatively soft (low fragmentation) ways of obtaining ions of large molecules in the gas phase, though MALDI typically produces far fewer multi-charged ions. MALDI methodology is a three-step process. First, the sample is mixed with a suitable matrix material and applied to a metal plate. Second, a pulsed laser irradiates the sample, triggering ablation and desorption of the sample and matrix materi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metastable
In chemistry and physics, metastability denotes an intermediate Energy level, energetic state within a dynamical system other than the system's ground state, 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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