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

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 15N isotopic substitution. The absorption spectra of the C and the A centres are the sum of a mode transforming as A1 and E at a C3v and D3d symmetrical defect respectively. The absorption spectrum of the B defect is due to the interaction with modes transforming as T2 at a Td 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.

► This paper give insight in the infrared absorption properties of nitrogen related defects in diamond. ► It explains the presence of absorption with frequencies higher than the Raman frequency in diamond by nitrogen defects ► It explains the presence of the local mode of single substitutional nitrogen as experimentally observed.