Double resonance NMR-on study on oriented188Ir in iron

The quadrupole splitting of oriented¹⁸⁸Ir in iron was studied at 8.6 mK using a double resonance NMR-ON method. With r.f. power applied at the strongest resonance frequency, a second frequency was used to simultaneously investigate the second resonance component, where the splitting is caused by an electric quadrupole interaction. The electric hyperfine splitting frequency ν_Q=e ² qQ/h was measured to be 3.37(11) MHz. With the known electric field gradient of −0.283(6)×10¹⁷ V/cm² at Ir in iron, the spectroscopic quadrupole moment of¹⁸⁸Ir was deduced to be 0.492(26)b. The present results show that the double resonance method is a powerful tool in establishing the quadrupole splitting, if it leads to well-resolved NMR-ON resonance components.