Careful control of the process parameters during CVD diamond synthesis allows growth of diamond films with different morphologies and preferred orientations, It has been lately shown that the addition of small concentrations of nitrogen to the process gas mixture can change the morphology of the deposit by favouring the growth of the diamond film in the [100] direction, On the other hand, higher nitrogen concentrations lead to the deterioration of the diamond him quality. The aim of this work is to correlate nitrogen concentrations in the process gas mixture to the emission intensities of nitrogen containing radicals (N-2 C-3 Pi(u)-B-3 Pi(g) system and CN B-2 Sigma-X(2) Sigma violet system) and carbon containing radicals (CH A(2) Delta-X(2) Pi system and C-2 Swan system). Scanning Electron Microscopy (SEM) is used to study the influence of nitrogen on the diamond him morphology.