Lattice location of Fe in diamond

Incorporation of radioactive $^{59}$Fe atoms in diamond was achieved by implanting precursor $^{59}$Mn isotopes, with an energy of 60 keV and to a dose of 8 $\times 10^{12}$ cm$^{-2}$, into a natural type IIa diamond sample at the online isotope separator ISOLDE at CERN. The lattice sites taken up by the Fe atoms, following $^{59}$Mn $\beta^{-}$-decays, have been investigated using the emission channeling (EC) technique. Channeling measurements were made on the electrons emitted in the $^{59}$Fe $\beta^{-}$-decay. Data were collected with a two-dimensional Si pad detector, along <110>, <100> and <111> axial directions from the as-implanted sample and after annealing in vacuum at 600$^\circ$K, 900$^\circ$K and 1250$^\circ$K. The channeling effects showed considerable enhancement with annealing. Fits to the observed patterns with simulations based on the many beam formalism of electron motion through a crystal lattice, show that, after annealing at 1250$^\circ$K, 65(5)% of the Fe atoms are located at sites with a projected mean displacement $\leq$ 0.2 Å from substitutional sites.