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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 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.
Considering these techniques from the opposite perspective, that magnetization (i.e. spin polarization) is being transferred from the bulk water to the spin-saturated hydration population, allows one to conceptually unify chemical exchange methods with other techniques that transfer magnetization between nuclei populations.
CIDNP (chemically induced dynamic nuclear polarization), often pronounced like "kidnip", is a nuclear magnetic resonance (NMR) technique that is used to study chemical reactions that involve radicals. It detects the non-Boltzmann (non-thermal) nuclear spin state distribution produced in these reactions as enhanced absorption or emission signals.
Finally, the free induction decay (FID) of the X nuclei is detected, typically with 1 H decoupling. Cross-polarization ( CP ), originally published as proton-enhanced nuclear induction spectroscopy ( PENIS ) [ 1 ] [ 2 ] is a solid-state nuclear magnetic resonance (ssNMR) technique to transfer nuclear magnetization from different types of nuclei ...
At the same time, such spectra lack quantitative information about the atomic ratios of different types of carbon nuclei, because nuclear Overhauser effect used in 1H-decoupled 13C-NMR spectroscopy enhances the signals from carbon atoms with a larger number of hydrogen atoms attached to them more than from carbon atoms with a smaller number of ...