Secondary signals in two-frequency nuclear quadrupole resonance on 14N nuclei with IÂ =Â 1

Our experimental and theoretical studies show that using two-frequency excitation of 14N nuclei it is possible to observe secondary NQR signals at one of the three possible transitions due to irradiation of another adjacent transition. As a result of the pulse sequence applied to the adjacent transition the spin-echo signals on the detected transition are observed after essential time interval from the initial single pulse on this frequency. Experiments have been performed on the 14N nuclei in the sodium nitrite (NaNO2) and the military explosive hexahydro-1,3,5-trinitro-s-triazine C3H6N6O6 (RDX).