enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Shim (magnetism) - Wikipedia

    en.wikipedia.org/wiki/Shim_(magnetism)

    In NMR and MRI, shimming is used prior to the operation of the magnet to eliminate inhomogeneities in its field. Initially, the magnetic field inside an NMR spectrometer or MRI scanner will be far from homogeneous compared with an "ideal" field of the device. This is a result of production tolerances and of the magnetic field of the environment.

  3. Nuclear magnetic resonance spectroscopy - Wikipedia

    en.wikipedia.org/wiki/Nuclear_magnetic_resonance...

    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.

  4. Quantum mechanics of nuclear magnetic resonance (NMR ...

    en.wikipedia.org/wiki/Quantum_mechanics_of...

    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 zero, [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.

  5. Free induction decay - Wikipedia

    en.wikipedia.org/wiki/Free_induction_decay

    Free induction decay (FID) nuclear magnetic resonance signal seen from a well shimmed sample. In Fourier transform nuclear magnetic resonance spectroscopy, free induction decay (FID) is the observable nuclear magnetic resonance (NMR) signal generated by non-equilibrium nuclear spin magnetization precessing about the magnetic field (conventionally along z).

  6. Shim (spacer) - Wikipedia

    en.wikipedia.org/wiki/Shim_(spacer)

    A shim is a thin and often tapered or wedged piece of material, used to fill small gaps or spaces between objects. [1] Shims are typically used in order to support, adjust for better fit, or provide a level surface. Shims may also be used as spacers to fill gaps between parts subject to wear.

  7. Paramagnetic nuclear magnetic resonance spectroscopy

    en.wikipedia.org/wiki/Paramagnetic_nuclear...

    Paramagnetic nuclear magnetic resonance spectroscopy refers to nuclear magnetic resonance (NMR) spectroscopy of paramagnetic compounds. [1] [2] Although most NMR measurements are conducted on diamagnetic compounds, paramagnetic samples are also amenable to analysis and give rise to special effects indicated by a wide chemical shift range and broadened signals.

  8. Nuclear magnetic resonance crystallography - Wikipedia

    en.wikipedia.org/wiki/Nuclear_magnetic_resonance...

    The spin interaction that is usually employed for structural analyses via solid state NMR spectroscopy is the magnetic dipolar interaction. [8] Additional knowledge about other interactions within the studied system like the chemical shift or the electric quadrupole interaction can be helpful as well, and in some cases solely the chemical shift has been employed as e.g. for zeolites. [9]

  9. Magnetic inequivalence - Wikipedia

    en.wikipedia.org/wiki/Magnetic_inequivalence

    In the context of nuclear magnetic resonance (NMR), the term magnetic inequivalence refers to the distinction between magnetically active nuclear spins by their NMR signals, owing to a difference in either chemical shift (magnetic inequivalence by the chemical shift criterion) or spin–spin coupling (magnetic inequivalence by the coupling criterion).