The fluorescence excitation of single N-V defect centres was described in terms of a double-well potential model which took account of the possibility of tunnelling of the N atom into the vacancy; in both the ground and excited electronic states of the centre. Fluorescence and linear absorption spectra were calculated and the double-well potential parameter values for N-V centres were determined. The effects of their variation, due to local diamond lattice distortions in the fluorescence spectra of various single N-V centres, were studied.

Spectroscopy of Single N-V Defect Centres in Diamond - Tunnelling of Nitrogen Atoms into Vacancies and Fluorescence Spectra. S.U.Kilin, A.P.Nizovtsev, T.M.Maevskaya, A.Drabenstedt, J.Wrachtrup: Journal of Luminescence, 2000, 86[3-4], 201-6