FUNDAMENTAL MECHANISMS OF SINGLE-PULSE NMR ECHO FORMATION

Citation
Ln. Shakhmuratova et al., FUNDAMENTAL MECHANISMS OF SINGLE-PULSE NMR ECHO FORMATION, Physical review. A, 55(4), 1997, pp. 2955-2967
Citations number
23
Categorie Soggetti
Physics
Journal title
ISSN journal
10502947
Volume
55
Issue
4
Year of publication
1997
Pages
2955 - 2967
Database
ISI
SICI code
1050-2947(1997)55:4<2955:FMOSNE>2.0.ZU;2-V
Abstract
A theoretical investigation of the formation of the so-called single p ulse NMR echo has been undertaken in the presence of both Larmor and R abi frequency inhomogeneities. It is found that this echo phenomenon, together with weaker, equally spaced secondary echoes, evolves from mu ltiple-pulse excitation under certain constraints with respect to inte rpulse time intervals compared with longitudinal and transverse relaxa tion times. These transient coherences arise from a complex superposit ion of oscillatory free induction decays, which extend further into th e time domain because of cumulative dephasing within each pulse in a m ultiple-pulse sequence. The effect is present for large Larmor inhomog eneity in isolation, but is stronger in the simultaneous presence of b oth frequency inhomogeneities, characteristic of ferromagnets. Predict ions of this model analysis are confirmed through experiment via conve ntional, zero-field, pulsed NMR on binary (VFe)-V-51 and pure elementa ry (enriched) (FeFe)-Fe-57 ferromagnets.