Influence of the molecular environment on the hyperfine interaction of 111Cd ions in gaseous radioactive 111InI3 Original Research Article

The hyperfine interaction (HFI) of 111Cd in gaseous InI3 systems was studied using perturbed angular correlation (PAC) measurements. The electron capture decay of 111In in InI3 followed by Coulomb fragmentation of the molecule produces an excited 111Cd ion. The nucleus decays to the ground state via γ-γ cascade the angular correlation of which is perturbed due to HFI. Collisions of the ion with InI3 molecules can strongly change the perturbation. The attenuation coefficient G22(∞) varies between 0.09 and 0.87 for molecular densities between 1014 and 1020 cm−3. G22(t) shows a similar behaviour. The present investigation has yielded an unexpected temperature dependence of the perturbation that had not been observed in previous experiments with InI, InCl, and InCl3 systems. A possible explanation is that the ionʹs charge may be lower if the 111In atom was part of a dimeric (In2I6) molecule before decay.