Fe-N films containing up to 70% a'-Fel6N2 were prepared by annealing N-implanted Fe layers on Si. Quantitative phase identification was performed by Mossbauer spectroscopy. The magnetic properties of the a" phase were deduced from magnetization measurements. The average magnetic moment per iron atom was about 15% higher than for pure a-Fe, which is in agreement with theoretical predictions. In contrast with earlier reports on a" grown by molecular beam epitaxy, the ion-beam-synthesized a" did not show giant magnetic moments.