Implantation of labelled single nitrogen vacancy centers in diamond   using 15N
  Nitrogen-vacancy (NV-) color centers in diamond were created by implantation of 7 keV 15N (I = 1/2) ions into type IIa diamond. Optically detected magnetic resonance was employed to measure the hyperfine coupling of the NV- centers. The hyperfine spectrum from 15NV- arising from implanted 15N can be distinguished from 14NV- centers created by native 14N (I = 1) sites. Analysis indicates 1 in 40 implanted 15N atoms give rise to an optically observable 15NV- center. This report ultimately demonstrates a mechanism by which the yield of NV- center formation by nitrogen implantation can be measured. 
J. R. Rabeau*, P. Reichart, G. Tamanyan, D. N. Jamieson, S. Prawer, F.   Jelezko, T. Gaebel, I. Popa, M. Domhan, J. Wrachtrup