Using pulsed optically detected magnetic resonance techniques, electron-spin resonance transitions in the excited-state of single nitrogen-vacancy colour centers in diamond were probed directly. An unambiguous assignment of excited-state fine structure was made; based upon changes in nitrogen-vacancy defect photoluminescence lifetimes. This study provided a significant insight into the structure of the emitting 3E excited state, which was invaluable for the development of diamond-based quantum information processing.

Excited-State Spectroscopy of Single NV Defects in Diamond Using Optically Detected Magnetic Resonance. P.Neumann, R.Kolesov, V.Jacques, J.Beck, J.Tisler, A.Batalov, L.Rogers, N.B.Manson, G.Balasubramanian, F.Jelezko, J.Wrachtrup: New Journal of Physics, 2009, 11[1], 013017