Pulsed field gradient
From Wikipedia, the free encyclopedia
A Pulsed field gradient is a short, timed pulse with spatial dependent field intensity. Any gradient is identified by four characteristics: axis, strength, shape and duration.
Pulsed field gradient (PFG) techniques are key to magnetic resonance imaging, spatially selective spectroscopy and studies of diffusion via NMR. PFG techniques are widely used as an alternative to phase cycling in modern NMR spectroscopy.
[edit] Common field gradients in NMR
The effect of a linear z-gradient on spin I, is considered to be a rotation around z-axis by an angle = γIGz; where G is the gradient strength and γI is the gyromagnetic ratio of spin I. It introduces a phase factor to the magnetizations:
Φ (z,τ) = γIzGτ
The time duration is usually 100s of µs or a few ms.
[edit] See also
 |
This physics-related article is a stub. You can help Wikipedia by expanding it. |
