Channeling of conversion electrons from radioactive impurities for analysis of atomic structures in solids
The channeling effect of conversion electrons emitted from implanted radioactive 111In impurities was investigated in Cu, Mo and Au and compared with calculations based on the dynamical theory of electron diffraction. From these calculations electron channeling turns out to be most sensitive to small displacements of impurities from substitutional sites as happens in the case of vacancy trapping. The combined application of perturbed γγ-angular correlation (PAC) and electron channeling employing 111In for the analysis of vacancy trapping configurations in Cu is demonstrated in an annealing experiment in recovery stage III after H + irradiation. A fraction of about 20% of probe atoms at tetrahedral interstitial sites and indications for small displacements of about 0.2 Å of substitutional impurities due to monovacancy trapping were found at an annealing temperature of 250 K.