Quadrupole couplings ofN12andB12implanted in metal single crystals

Measurements have been made of the quadrupole couplings of ${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$ implanted in single crystals of Be and Mg and of ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ implanted in a single crystal of Zn. A comparison of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$ couplings in Be and Mg suggests that (i) the final stopping sites of the implanted ${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$ ions are substitutional sites, i.e., the ${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$ ions occupy metal-ion lattice positions, and (ii) the ${}_{}{}^{12}{}_{}{}^{}\mathrm{N}$ ions implanted in Be and Mg have the same charge state and quadrupole shielding factor. A procedure is outlined for deducing $Q\left({}_{}{}^{12}{}_{}{}^{}\mathrm{N}\right)$. The ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ couplings in Zn imply the existence of two inequivalent stopping sites. The problems encountered in deducing $Q\left({}_{}{}^{12}{}_{}{}^{}\mathrm{B}\right)$ from couplings in metal hexagonal crystals are discussed.