The modes of the one phonon infrared absorption spectra of nitrogen aggregate defects in diamond

Abstract The mid-IR absorption spectra of various nitrogen aggregate defects in diamond are calculated, starting from the vibrational density of states, and compared to the experimental spectrum of these defects. The single substitutional 1344 cm −1 peak is a local mode transforming as E, and does not shift with 15 N isotopic substitution. The absorption spectra of the C and the A centres are the sum of a mode transforming as A 1 and E at a C 3v and D 3d symmetrical defect respectively. The absorption spectrum of the B defect is due to the interaction with modes transforming as T 2 at a T d defect. The maxima at 1095 cm −1 appearing in the absorption spectra of all types of nitrogen aggregates is completely determined by the total mass, the symmetry and the position of the various maxima in the vibrational density of states.