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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]
Graphical representation of the INEPT NMR pulse sequence. INEPT is utilized often to improve 15 N resolution because it can accommodate negative gyromagnetic ratios, increases Boltzmann polarization, and decreases T 1 relaxation. [3] Insensitive nuclei enhanced by polarization transfer (INEPT) is a signal
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.
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.
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.
The 13 C polarization levels in solid compounds can reach up to ≈64% and the losses during dissolution and transfer of the sample for NMR measurements can be minimized to a few percent. [43] Compounds containing NMR-active nuclei can also be hyperpolarized using chemical reactions with para-hydrogen, see Para-Hydrogen Induced Polarization (PHIP).
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 ...
The above reaction involves "mirror nuclei", nuclei in which the numbers of protons and neutrons are interchanged. One can measure the angular distributions of β particles with respect to the axis of nuclear spin polarization to determine what the mixture is between the two decay types (Fermi and Gamow–Teller).