Time-Differential Quadrupole Interaction ofCd111Nuclei Implanted by (α,2n) Reactions into a Cubic Ag Lattice

Abstract

The quadrupole interaction of ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$ ions following the decay of ${}_{}{}^{111}{}_{}{}^{}\mathrm{In}$ implanted by ($\alpha ,2n$) reactions into a cubic (fcc) Ag lattice has been measured with the time-differential perturbed-angular-correlation method. A nonvanishing quadrupole interaction corresponding to a distribution of electric field gradients was observed. The "smeared out" quadrupole interaction frequency has a centroid $\overline{\omega }$ from 2.04 to 1.50 MHz depending on the temperature and the time the irradiated Ag was allowed to "heal." In addition, about 3% of the ${}_{}{}^{111}{}_{}{}^{}\mathrm{In}$-${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$ ions experience a quadrupole interaction with a sharp frequency ${\omega }_Q=157\mathrm{}\pm 2$ MHz. The temperature dependence of the healing process was investigated. At room temperature no further healing occurs after 6 days once the $\overline{\omega }=1.50\mathrm{}$ MHz was reached. Annealing for 12 hours at 600°C causes the quadrupole interaction to vanish conpletely. Various quadrupole-perturbation and "healing" mechanisms are discussed. The most likely cause of the quadrupole perturbation in the cubic Ag lattice are vacancies and/or Ag interstitials.