Depletion of nitrogen-vacancy color centers in diamond via hydrogen   passivation
  We show a marked reduction in the emission from nitrogen-vacancy (NV) color centers in single crystal diamond due to exposure of the diamond to hydrogen plasmas ranging from 700{\deg}C to 1000{\deg}C. Significant fluorescence reduction was observed beneath the exposed surface to at least 80mm depth after ~10 minutes, and did not recover after post-annealing in vacuum for seven hours at 1100{\deg}C. We attribute the fluorescence reduction to the formation of NVH centers by the plasma induced diffusion of hydrogen. These results have important implications for the formation of nitrogen-vacancy centers for quantum applications, and inform our understanding of the conversion of nitrogen-vacancy to NVH, whilst also providing the first experimental evidence of long range hydrogen diffusion through intrinsic high-purity diamond material. 
A. Stacey, T.J. Karle, L.P. McGuinness, B.C. Gibson, K. Ganesan, S.   Tomljenovic-Hanic, A.D. Greentree, S. Prawer, R.G. Bea...
cond-mat.mtrl-sci quant-ph