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Generally, the g-factors are very difficult to calculate for such many-body systems, but they have been measured to high precision for most nuclei. The Larmor frequency is important in NMR spectroscopy. The gyromagnetic ratios, which give the Larmor frequencies at a given magnetic field strength, have been measured and tabulated. [3]
These procedures rely on the fact that bulk magnetization due to nuclear spins precess in a magnetic field at a rate called the Larmor frequency, which is simply the product of the gyromagnetic ratio with the magnetic field strength. With this phenomenon, the sign of γ determines the sense (clockwise vs counterclockwise) of precession.
The power is absorbed by the precessing magnetization (Larmor precession) of the material and lost as heat. For this coupling to occur, the frequency of the incident wave must be equal to the precession frequency of the magnetization (Larmor frequency) and the polarization of the wave must match the orientation of the magnetization.
The geomagnetic field strength and hence precession frequency varies with location and time. Larmor precession frequency = magnetogyric ratio x magnetic field Proton magnetogyric ratio = 42.576 Hz/μT (also written 42.576 MHz/T or 0.042576 Hz/nT) Earth's magnetic field: 30 μT near Equator to 60 μT near Poles, around 50 μT at mid-latitudes.
If a horizontal rotating field , angular frequency of rotation is applied in the region between poles of magnet 2, produced by oscillating current in circular coils then there is a probability for the atoms passing through there from one spin state to another (= + / > / and vice versa), when = , Larmor frequency of precession of magnetic moment ...
The gyromagnetic ratio is also the ratio between the observed angular frequency of Larmor precession and the strength of the magnetic field in nuclear magnetic resonance applications, [39] such as in MRI imaging. For this reason, the quantity γ/2π called "gamma bar", expressed in the unit MHz/T, is often given.
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).
The precession frequency is known as the Larmor frequency ω L. [5] = where γ is the gyromagnetic ratio and B 0 the magnetic field. The electron spins are characterized by two quantum mechanical states, one parallel and one antiparallel to B 0.