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Cross-polarization
Cross-polarization (CP), originally published in 1962 as nuclear double resonance in the rotating frame by Hartmann and Hahn is a solid-state nuclear magnetic resonance (ssNMR) technique used to transfer nuclear magnetization from different types of nuclei via heteronuclear dipolar interactions. The 1H-X cross-polarization dramatically improves the sensitivity of ssNMR experiments of most experiments involving spin-1/2 nuclei, capitalizing on the higher 1H polarization, and shorter T1(1H) relaxation times. In 1972 CP was crucially adapted to magic angle spinning (MAS) by Michael Gibby, Alexander Pines and John S. Waugh at the Massachusetts Institute of Technology who adapted a variant of the Hartmann and Hahn experiment designed by Lurie and Slichter. The technique is now widely known as CPMAS. In CP, the natural nuclear polarization of an abundant spin (typically 1H) is exploited to increase the polarization of a rare spin (such as 13C, 15N, 31P) by irradiating the sample w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid-state Nuclear Magnetic Resonance
Solid-state nuclear magnetic resonance (ssNMR) is a spectroscopy technique used to characterize atomic-level structure and dynamics in solid materials. ssNMR spectra are broader due to nuclear spin interactions which can be categorized as dipolar coupling, chemical shielding, quadrupolar interactions, and j-coupling. These interactions directly affect the lines shapes of experimental ssNMR spectra which can be seen in powder and dipolar patterns. There are many essential solid-state techniques alongside advanced ssNMR techniques that may be applied to elucidate the fundamental aspects of solid materials. ssNMR is often combined with magic angle spinning (MAS) to remove anisotropic interactions and improve the sensitivity of the technique. The applications of ssNMR further extend to biology and medicine. Nuclear spin interactions The resonance frequency of a nuclear spin depends on the strength of the magnetic field at the nucleus, which can be modified by isotropic (e.g. c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cross-polarization
Cross-polarization (CP), originally published in 1962 as nuclear double resonance in the rotating frame by Hartmann and Hahn is a solid-state nuclear magnetic resonance (ssNMR) technique used to transfer nuclear magnetization from different types of nuclei via heteronuclear dipolar interactions. The 1H-X cross-polarization dramatically improves the sensitivity of ssNMR experiments of most experiments involving spin-1/2 nuclei, capitalizing on the higher 1H polarization, and shorter T1(1H) relaxation times. In 1972 CP was crucially adapted to magic angle spinning (MAS) by Michael Gibby, Alexander Pines and John S. Waugh at the Massachusetts Institute of Technology who adapted a variant of the Hartmann and Hahn experiment designed by Lurie and Slichter. The technique is now widely known as CPMAS. In CP, the natural nuclear polarization of an abundant spin (typically 1H) is exploited to increase the polarization of a rare spin (such as 13C, 15N, 31P) by irradiating the sample w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Pines
Alexander Pines (; June 22, 1945 – November 1, 2024) was an American chemist. He was the Glenn T. Seaborg Professor Emeritus, University of California, Berkeley, Chancellor's Professor Emeritus and Professor of the Graduate School, University of California, Berkeley, and a member of the California Institute for Quantitative Biosciences (QB3) and the Department of Bioengineering. Background Pines was born on June 22, 1945, and grew up in Bulawayo in Southern Rhodesia (now Zimbabwe). He studied undergraduate mathematics and chemistry in Israel at Hebrew University of Jerusalem. Coming to the United States in 1968, Pines obtained his Ph.D. in chemical physics at M.I.T. in 1972 and joined the UC Berkeley faculty later that year. Pines died on November 1, 2024, at the age of 79. Research Pines was a pioneer in the development and applications of nuclear magnetic resonance (NMR) spectroscopy of non-liquid samples. In his early work, he demonstrated time-reversal of dipole-dipo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magic Angle Spinning
In solid-state NMR spectroscopy, magic-angle spinning (MAS) is a technique routinely used to produce better resolution NMR spectra. MAS NMR consists in spinning the sample (usually at a frequency of 1 to 130 kHz) at the magic angle θm (ca. 54.74°, where cos2θm=1/3) with respect to the direction of the magnetic field. Three main interactions responsible in solid state NMR ( dipolar, chemical shift anisotropy, quadrupolar) often lead to very broad and featureless NMR lines. However, these three interactions in solids are orientation-dependent and can be averaged to some extent by MAS: * The nuclear dipolar interaction has a 3\cos^2\theta - 1 dependence, where \theta is the angle between the internuclear axis and the main magnetic field. As a result, the dipolar interaction vanish at the magic angle θm and the interaction contributing to the line broadening is removed. Even though all internuclear vectors cannot be all set to the magic angle, rotating the sample around ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John S
John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second Epistle of John, often shortened to 2 John * Third Epistle of John, often shortened to 3 John People * John the Baptist (died ), regarded as a prophet and the forerunner of Jesus Christ * John the Apostle (died ), one of the twelve apostles of Jesus Christ * John the Evangelist, assigned author of the Fourth Gospel, once identified with the Apostle * John of Patmos, also known as John the Divine or John the Revelator, the author of the Book of Revelation, once identified with the Apostle * John the Presbyter, a figure either identified with or distinguished from the Apostle, the Evangelist and John of Patmos Other people with the given name Religious figures * John, father of Andrew the Apostle and Saint Peter * Pope John (disambigu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Massachusetts Institute Of Technology
The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and science. In response to the increasing Technological and industrial history of the United States, industrialization of the United States, William Barton Rogers organized a school in Boston to create "useful knowledge." Initially funded by a land-grant universities, federal land grant, the institute adopted a Polytechnic, polytechnic model that stressed laboratory instruction in applied science and engineering. MIT moved from Boston to Cambridge in 1916 and grew rapidly through collaboration with private industry, military branches, and new federal basic research agencies, the formation of which was influenced by MIT faculty like Vannevar Bush. In the late twentieth century, MIT became a leading center for research in compu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Pence Slichter
Charles Pence Slichter (January 21, 1924 – February 19, 2018) was an American physicist, best known for his work on nuclear magnetic resonance and superconductivity. He was awarded the 2007 National Medal of Science "for establishing nuclear magnetic resonance as a powerful tool to reveal the fundamental molecular properties of liquids and solids. His inspired teaching has led generations of physicists and chemists to develop a host of modern technologies in condensed matter physics, chemistry, biology and medicine." Birth and education Slichter was born in 1924 in Ithaca, New York. He attended Harvard University, where in 1949 received his Ph.D. under the supervision of Edward Purcell. Career Slichter was a professor of physics and chemistry at the University of Illinois at Urbana-Champaign from 1949 until his retirement in 2006. He spent one sabbatical semester (Spring 1961) as Morris Loeb Lecturer at Harvard University. The lectures he gave there formed the nucleus of h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hartmann Hahn
Hartmann is a German surname. It is less frequently used as a male given name. The name originates from the Germanic word, "hart", which translates in English to "hardy", "hard", or "tough" and "Mann", a suffix meaning "man", "person", or "husband". The name Hartman, distinguished by ending with a single "n", is generally the result of the anglicisation of names that occurred with the emigration of persons from German-speaking to anglophone nations in the 18th, 19th and early 20th century. Below is a list of notable individuals and fictional characters with the surname or given name of Hartmann. Arts and media * Hartmann von Aue (c. 1170 – c. 1210) German poet * Lukas Hartmann (1944), Swiss novelist and children's literature writer * Moritz Hartmann (1821–1872), Bohemian-Austrian Jewish poet * Oluf Hartmann (1879–1910), Danish painter * Petra Hartmann (born 1970), German author and literature scientist * Sadakichi Hartmann (1867–1944), German-Japanese art critic long resi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spin Polarization
In particle physics, spin polarization is the degree to which the spin, i.e., the intrinsic angular momentum of elementary particles, is aligned with a given direction. This property may pertain to the spin, hence to the magnetic moment, of conduction electrons in ferromagnetic metals, such as iron, giving rise to spin-polarized currents. It may refer to (static) spin waves, preferential correlation of spin orientation with ordered lattices (semiconductors or insulators). It may also pertain to beams of particles, produced for particular aims, such as polarized neutron scattering or muon spin spectroscopy. Spin polarization of electrons or of nuclei, often called simply magnetization, is also produced by the application of a magnetic field. Curie law is used to produce an induction signal in electron spin resonance (ESR or EPR) and in nuclear magnetic resonance (NMR). Spin polarization is also important for spintronics, a branch of electronics. Magnetic semiconducto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spin (physics)
Spin is an Intrinsic and extrinsic properties, intrinsic form of angular momentum carried by elementary particles, and thus by List of particles#Composite particles, composite particles such as hadrons, atomic nucleus, atomic nuclei, and atoms. Spin is quantized, and accurate models for the interaction with spin require relativistic quantum mechanics or quantum field theory. The existence of electron spin angular momentum is inferred from experiments, such as the Stern–Gerlach experiment, in which silver atoms were observed to possess two possible discrete angular momenta despite having no orbital angular momentum. The relativistic spin–statistics theorem connects electron spin quantization to the Pauli exclusion principle: observations of exclusion imply half-integer spin, and observations of half-integer spin imply exclusion. Spin is described mathematically as a vector for some particles such as photons, and as a spinor or bispinor for other particles such as electrons. Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyromagnetic Ratio
In physics, the gyromagnetic ratio (also sometimes known as the magnetogyric ratio in other disciplines) of a particle or system is the ratio of its magnetic moment to its angular momentum, and it is often denoted by the symbol , gamma. Its SI unit is the reciprocal second per tesla (s−1⋅T−1) or, equivalently, the coulomb per kilogram (C⋅kg−1). The -factor of a particle is a related dimensionless value of the system, derived as the ratio of its gyromagnetic ratio to that which would be classically expected from a rigid body of which the mass and charge are distributed identically, and for which total mass and charge are the same as that of the system. For a classical rotating body Consider a nonconductive charged body rotating about an axis of symmetry. According to the laws of classical physics, it has both a magnetic dipole moment due to the movement of charge and an angular momentum due to the movement of mass arising from its rotation. It can be shown that as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Magnetic Resonance
Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca. 20 tesla, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz). NMR results from specific magnetic properties of certain atomic nuclei. High-resolution nuclear magnetic resonance spectroscopy is widely used to determine the structure of organic molecules in solution and study molecular physics and crystals as well as non-crysta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
