New infrared emission of the NV centre in diamond: Zeeman and uniaxial   stress studies
  An emission band in the infrared is shown to be associated with a transition within the negative nitrogen-vacancy center in diamond. The band has a zero-phonon line at 1046 nm, and uniaxial stress and magnetic field measurements indicate that the emission is associated with a transition between 1E and 1A1 singlet levels. Inter-system crossing to these singlets causes the spin polarisation that makes the NV- centre attractive for quantum information processing, and the infrared emission band provides a new avenue for using the centre in such applications. 
L. J. Rogers and S. Armstrong and M. J. Sellars and N. B. Manson