Infra-red studies were made of samples which were lightly doped with N and H. As a result, a trigonal defect that involved N and a pair of non-equivalent H atoms was identified. This had local vibrational modes at 2885.5, 2054.1 and 1049.8/cm for the 14N-related complex, and 14N-15N isotopic shifts were observed for the 2 high wave-number modes. All of the modes were attributed to a defect with one H atom in a bond-centered site and the other in an anti-bonding position around the N atom. The two H atoms were bonded mainly to the same N atom.

B.Clerjaud, D.Côte, W.S.Hahn, A.Lebkiri, W.Ulrici, D.Wasik: Physical Review Letters, 1996, 77[24], 4930-3