An apparatus and method for producing a multi-pulse sequence for
irradiating a substance provided with quadrupole nuclei with either
integer or half-integer spins to detect an NQR signal emitted therefrom.
The apparatus has pulse sequence generating means adapted to produce
multi-pulse sequences with pulse intervals exceeding T.sub.2* and
containing a preparatory pulse or group of pulses for creating echo
signals between the pulses. The pulse sequence is organised so that the
resulting signal contains a prevailing echo component produced by the
preparatory pulse or group of pulses.
