Quadrupole Interaction of 181Ta in Hafnium Oxychloride

The static electric quadrupole interaction of 181 Ta in HfOCl 2 ∙8H 2 O and HfOCl 2 ∙4H 2 O, incorporating the perturbed angular correlation of the 133–482 keV γ-rays cascade, has been measured. The quadrupole interaction frequencies obtained were ω 1 = (1356 ± 65) mrad/s for HfOCl 2 ∙8H 2 O, and ω 1 = (858 ± 40) mrad/s, η = 0.58 ± 0.01 for HfOCl 2 ∙4H 2 O. Comparison with other measurements is given.