N-14 NUCLEAR-QUADRUPOLE RESONANCE IN ANTI-FERROMAGNETIC CU(HCOO)2.2(NH2)2CO.2H2O

The temperature dependence of 14N NQR frequencies was determined for Cu(HCOO)2·2(NH2)2CO·2H 2O in the temperature range 2-90 K. Two sets of vI and vII lines of 14N NQR frequencies were detected at the various temperatures studied, indicating that there exist two different kinds of nitrogen sites in the crystal in agreement with the crystal structure determined at room temperature. An anomalous frequency shift attributable to Zeeman interaction was observed for all the lines detected in the antiferromagnetic phase below 16 K. The spin structure of the ordered state and the internal field at the two different nitrogen sites were deduced from the shift of the resonance frequencies. © 1979 American Chemical Society.