Diffusion measurements with the aid of nutation spin echoes appearing after two inhomogeneous radiofrequency pulses in inhomogeneous magnetic fields

Nutation echoes are generated by radiofrequency (RF) pulses with an inhomog eneous 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 al igned in parallel for a maximum echo signal. After two RF pulses, two echoe s appear at times tau (a) = 2 tau (1) + tau (2) + (G(1)/G(0))tau (1) and ta u (b) = 2 tau (1) + tau (2) + 2(G(1)/G(0))tau (1), where tau (1) is the RF pulse duration and I, the interpulse interval. It is shown that these echoe s can favorably be employed for the determination of self-diffusion coeffic ients even in the poor experimental situation one often faces in low-resolu tion or low-field NMR. The signal intensity is comparable to that of ordina ry Hahn echoes. Diffusion coefficients and spin-lattice relaxation times ca n 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, surfac e coil NMR, toroid cavity NMR, etc., are suggested. (C) 2001 Academic Press .