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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.
When electron spin polarization deviates from its thermal equilibrium value, polarization transfers between electrons and nuclei can occur spontaneously through electron-nuclear cross relaxation or spin-state mixing among electrons and nuclei. For example, polarization transfer is spontaneous after a homolysis chemical reaction.
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 ...
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 ...
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 ...
Taking for example the H 2 O molecules in liquid phase without the contamination of oxygen-17, the value of K is 1.02×10 10 s −2 and the correlation time is on the order of picoseconds = s, while hydrogen nuclei 1 H at 1.5 tesla precess at a Larmor frequency of approximately 64 MHz (Simplified. BPP theory uses angular frequency indeed).