Time differential perturbed angular correlation (TDPAC) studies of the 133Ba ion uptake in bone crystals

TDPAC measurements of the 356-81 keV gamma-ray cascade resulting from electron capture decay of 133Ba have been performed at room temperature on BaCl2 (aqueous solution and polycrystalline powder), and on samples where the 133Ba nucleus is bound to bone powder, and also to synthesised hydroxylapatite, all after absorption in vitro. As expected, the angular correlation is not perturbed in the solution. However, in the polycrystalline chloride the time dependence of the anisotropy of the cascade of 133Cs nuclide indicates that the decaying nucleus undergoes electric interactions due to different electric field gradients acting at the site of the nucleus. In 133Ba-bone powder the results show a static quadrupolar interaction differing with the absorption contact time during sample preparation, indicating that depth of 133Ba ion fixation in the bone crystal is dependent on this contact time. These results seem to be confirmed by the TDPAC measurements performed on 133Ba-hydroxylapatite samples where the contact times for absorption of active-ion 133Ba and hydroxylapatite in suspension were very different.