Fig. 7
The main first-derivative EPR signal of D19 diamond crystals at low and high microwave powers (a), decomposition of the integrated EPR signal into components related to two groups of spins (b), and the corresponding saturation trend of the peak intensity of this EPR signal versus the square root of microwave power in the range up to 200 mW (c). The triplet HFS structure of the EPR signal of the P1 centre (substitutional nitrogen) is clearly distinguishable in (a). In (b): curve 3, having triplet structure, corresponds to the EPR spectrum of only P1 centres. In (c): the dashed straight line is the Ipp vs (PMW)1/2 dependence for DP 0–0.05 polycrystals given for reference. Four experimental points at PMW = 0.5, 1, 2, 4 mW were used for its plotting (two of them are not presented here). Microwave frequency ν = 9.44 GHz