Carbon nitride nanospheres have been synthesized into copper by simultaneous high fluence (10(18) at. cm(-2)) implantations of C-12 and N-15 ions. The composition of the implanted region has been measured using C-12(d,p(0))C-13 and N-15(d,alpha(0))C-13 nuclear reactions induced by a 1.05 MeV deuteron beam. The C-12 and N-15 depth profiles are very close and the retained doses into copper are relatively high, which indicates that carbon and nitrogen diffusion processes are likely limited during implantation. High resolution transmission electron microscopy (HRTEM) observations and electron diffraction (ED) analyses have been carried out to determine the structure of the nanospheres formed during implantation. Some consist in small hollow amorphous nanocapsules with sizes ranging from 30 to 100 nm. Large gas bubbles with diameters up to 300 mn have also been observed in the copper matrix. Electron energy-loss spectroscopy (EELS) measurements performed on the small nanocapsules indicate that their shells are composed of carbon and nitrogen. (c) 2007 Elsevier B.V. All rights reserved.