Hyperfine interactions of implanted nuclei in graphite observed by low temperature nuclear orientation

Abstract

Pure nuclear electric quadrupole interaction of ion-implanted 203 Hg and 188 Ir in Highly Oriented Pyrolytic Graphite layers has been observed in low temperature nuclear orientation experiments. The electric field gradients at the nuclear sites were found to be positive, with values of +0.79(17)×10 19 V/cm 2 (ν Q =0.66 (14) GHz) for 203 Hg and +0.788 (40)×10 19 V/cm 203 (ν Q =0.987 (40) GHz) for 188 Ir. At 4 mK, the anisotropies in the directional distribution of γ-rays from these isotopes were saturated, but only at 35.2 (2.4) % for 203 Hg, respectively 8.59(18)% for 188 Ir, of the expected maximum value.