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Insensitive nuclei enhancement by polarization transfer (INEPT) is a signal enhancement method used in NMR spectroscopy. It involves the transfer of nuclear spin polarization from spins with large Boltzmann population differences to nuclear spins of interest with lower Boltzmann population differences. [ 1 ]
The nuclear Overhauser effect (NOE) is the transfer of nuclear spin polarization from one population of spin-active nuclei (e.g. 1 H, 13 C, 15 N etc.) to another via cross-relaxation.
The HSQC experiment is a highly sensitive 2D-NMR experiment and was first described in a 1 H— 15 N system, but is also applicable to other nuclei such as 1 H— 13 C and 1 H— 31 P. The basic scheme of this experiment involves the transfer of magnetization on the proton to the second nucleus, which may be 15 N, 13 C or 31 P, via an INEPT ...
The sign of the gyromagnetic ratio, γ, determines the sense of precession. Nuclei such as 1 H and 13 C are said to have clockwise precession whereas 15 N has counterclockwise precession. [3] [4] Unlike most nuclei, the gyromagnetic ratio for 15 N is negative. With the spin precession phenomenon, the sign of γ determines the sense (clockwise ...
The linewidth is optimized for polarization transfer from electrons to nuclei, when it is close to the nuclear Larmor frequency. The optimization is related to an embedded three-spin (electron-electron-nucleus) process that mutually flips the coupled three spins under the energy conservation (mainly) of the Zeeman interactions.
A more specific example of this case is presented in the section Chemical Exchange Magnetization transfer. In either case, magnetization transfer techniques probe the dynamic relationship between two or more distinguishable nuclei populations, in so far as energy exchange between the populations can be induced and measured in an idealized NMR ...
Hyperpolarization is the spin polarization of the atomic nuclei of a material in a magnetic field far beyond thermal equilibrium conditions determined by the Boltzmann distribution. [1] It can be applied to gases such as 129 Xe and 3 He , and small molecules where the polarization levels can be enhanced by a factor of 10 4 –10 5 above thermal ...
In magnetic resonance imaging (MRI) and nuclear magnetic resonance spectroscopy (NMR), an observable nuclear spin polarization (magnetization) is created by a homogeneous magnetic field. This field makes the magnetic dipole moments of the sample precess at the resonance frequency of the nuclei. At thermal equilibrium, nuclear spins precess ...