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Using the 85–75 keV γγ-cascade of100Rh, we report the first DPAC measurement of the hyperfine field in100RhCo and100RhFe. Our results were made possible by continued improvement in time resolution using BaF2 scintillators. At room temperature we obtained fields of 420.6(1.3) kG and 540.4(1.5) kG for100RhCo and100RhFe, respectively. The former revises an earlier spin echo result by Kontani and Itoh by ∼9%; the latter is consistent with the work of Matthiaset al. using resonant destruction of angular correlations.

Using perturbed angular correlations we studied the formation of a cubic symmetry defect trap in Ni near 350 K following plastic deformation at 295 K. The trap has been identified structurally as a trivacancy trap. The evolution of the defect-free and cubic trap site populations in the course of isochronal and isothermal annealing experiments leads to the conclusion that the cubic trap forms by simple trapping, and that the capture radius of the cubic trap for additional defects is very small.

The quadrupole coupling frequency of an111In-defect bound state in Pt with ω0(295 K) = 200 Mrad/s was measured over the range 4 – 300 K using perturbed angular correlations. The temperature dependence exhibited positive curvature, unlike the T3/2 dependence observed in noncubic metals, and was fitted using a model which assumed that the temperature dependence was caused by vibrations of a resonant mode in the probe-defect complex.

Using BaF2 scintillation counters we made a series of DPAC measurements on99TcFe in the temperature range 77 < T < 1020 K. Our results at room temperature are consistent with earlier measurements of Raghavan and Raghavan. Contrary to earlier suppositions, Hhf(T) does not have an anomalous temperature dependence like that of OsFe.

BaF2 scintillation counters, coupled to constant fraction differential discriminatiors, permit simultaneous energy and timing decisions in recording delayed coincidence spectra. We explore the advantages and limitations of this innovation in time differential perturbed angular correlation experiments, and illustrate it for111CdNi and100RhNi.