The results of photoluminescence measurements on ZnO implanted with stable and radioactive isotopes of Zn and Ga are presented. The donor-related exciton feature I 8 at 3.3600 eV is suggested to be due to bound exciton recombination at Ga donors. The I 1 line at 3.3718 eV is also likely to be due to Ga, and is attributed to ionized Ga donor bound exciton recombination. A feature at 3.3225 eV is observed following transmutation of radioactive Ga into stable Ge, and is attributed to Ge. Finally, a damage-related band is observed in the region of 1.8 eV when the recoil energy of the decay is capable of dislodging the host atoms from their respective lattice sites.