Diffusion Measurements with the Aid of Nutation Spin Echoes Appearing after Two Inhomogeneous Radiofrequency Pulses in Inhomogeneous Magnetic Fields
✍ Scribed by Attila Scharfenecker; Ioan Ardelean; Rainer Kimmich
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 79 KB
- Volume
- 148
- Category
- Article
- ISSN
- 1090-7807
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✦ Synopsis
Nutation echoes are generated by radiofrequency (RF) pulses with an inhomogeneous amplitude, B 1 ؍ B 1 (r), in inhomogeneous magnetic fields, B 0 ؍ B 0 (r). The two gradients of strengths G 1 and G 0 , respectively, must be aligned in parallel for a maximum echo signal. After two RF pulses, two echoes appear at times
where 1 is the RF pulse duration and 2 the interpulse interval. It is shown that these echoes can favorably be employed for the determination of selfdiffusion coefficients even in the poor experimental situation one often faces in low-resolution or low-field NMR. The signal intensity is comparable to that of ordinary Hahn echoes. Diffusion coefficients and spin-lattice relaxation times can be evaluated from the same experimental data set if both nutation echoes are recorded. Test experiments are in good agreement with literature data. Applications of the technique to "inside out" NMR, well logging NMR, surface coil NMR, toroid cavity NMR, etc., are suggested.