Single-pulse and secondary echoes in systems with a large inhomogeneous broadening of NMR lines

Abstract

The possibility of comparatively simple and fast determination of characteristic relaxation parameters T 1 , T 2 and T 3 for nuclear spin-systems with strong Larmor and Rabi inhomogeneous broadenings of NMR lines using the secondary echo signal effect was experimentally shown. Resides, this method gives opportunity to obtain a valuable infomation on the inhomogeneous NMR broadening which reflects the character of magnetic field microscopic destribution in such systems, as example, multidomain magnetics and superconductors.Spin-echo phenomenon discovered by Hahn in 1950 [1] is now one of the most developed method of the nuclear magnetic resonance (NMR) and the electronic paramagnetic resonance effectively used for studying of physical properties of very different materials as metals, dielectrics semiconductors and so on.It is known that for observation of the Hahn echo at least two radio frequency (RF) pulses are necessary. It is also known that information on spin-system usually obtained with the help of two pulse Hahn echo (TPE) could be obtained by the singlepulse echo (SPE) [2,3]. But in a number of cases the most convenient proves to be the spin echo excitation by multipulse series of RF pulses which, in particular, provide an operative measurement of relaxation times T 1 and T 2 of the investigated systems [4].Recently in [5,4] the formation of secondary nuclear spin echo signals in systems with large Larmor and Rabi inhomogeneous broadenings of a NMR line at periodical