Spin echo in magnetics with a quadrupole-split NMR spectrum

A study is made of the characteristics of the formation of a nuclear spin echo in magnetics, with allowance for an inhomogeneity of the Zeeman and quadrupole splittings. The dependence of the echo amplitude on the carrier frequency of the exciting pulses is investigated for the spin I = 3/2. It is shown that the amplitude of the first echo has the maximum order of magnitude when the frequencies of the pulses are identical and coincide with the frequencies of one-photon transitions. The order of magnitude of the secondary echo is maximal if the frequency of the first pulse is the same as that of one of the resonance frequencies of the system, whereas the frequency of the second pulse coincides with the central line of an NMR spectrum