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NMR logging exploits the large magnetic moment of hydrogen, which is abundant in rocks in the form of water. The NMR signal amplitude is proportional to the quantity of hydrogen nuclei present in a formation and can be calibrated to give a value for porosity that is free from lithology effects.
A 900 MHz NMR instrument with a 21.1 T magnet at HWB-NMR, Birmingham, UK. Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy (MRS), is a spectroscopic technique based on re-orientation of atomic nuclei with non-zero nuclear spins in an external magnetic field.
Nuclear magnetic resonance (NMR) spectroscopy uses the intrinsic magnetic moment that arises from the spin angular momentum of a spin-active nucleus. [1] If the element of interest has a nuclear spin that is not 0, [1] the nucleus may exist in different spin angular momentum states, where the energy of these states can be affected by an external magnetic field.
Deuterated solvents permit the use of deuterium frequency-field lock (also known as deuterium lock or field lock) to offset the effect of the natural drift of the NMR's magnetic field . In order to provide deuterium lock, the NMR constantly monitors the deuterium signal resonance frequency from the solvent and makes changes to the B 0 ...
Solid-state 900 MHz (21.1 T [1]) NMR spectrometer at the Canadian National Ultrahigh-field NMR Facility for Solids. 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 ...
The difference between the chemical shift of a given nucleus in a diamagnetic vs. a paramagnetic environment is called the hyperfine shift.In solution the isotropic hyperfine chemical shift for nickelocene is −255 ppm, which is the difference between the observed shift (ca. −260 ppm) and the shift observed for a diamagnetic analogue ferrocene (ca. 5 ppm).
The first generation of NMR spectrometers used large Electromagnets weighing hundreds of kilograms or more. Slightly smaller permanent magnet systems were developed in the 1960s-70s at proton resonance frequencies of 60 and 90 MHz and were widely used for chemical analysis using continuous wave methods, but these permanent magnets still weighed hundreds of kilograms and could not be placed on ...
On a properly acquired NMR spectrum this is seen as a narrow Lorentzian line (at 4.8 ppm, 20 C). Bulk water molecules are also relatively far from magnetic field perturbing macromolecules, such that free water protons experience a more homogeneous magnetic field, which results in slower transverse magnetization dephasing and a longer T 2 ...