Other than the overtone and combination bands, no other peaks have intensities that correlate with the intensity of the 3107 cm−1 and/or 1405 cm−1 peaks, thus one can assume the associated defect contains one H atom which is related to a single C-H stretching and bending frequency. As shown above, N does not bond to H (or H-bonded C) in this defect. However, the intensity of the 3107 cm−1 peak often shows a positive correlation with N content [42,61] and thus one can also assume N is involved in this defect. Moreover, the absence of the 3107 cm−1 peak in pure Type Ib diamonds suggest involvement of highly aggregated N (e.g. N3-centers, VN3 defects) or B-centers (VN4 defects) as opposed to C-centers (single substitutional N defects), see Appendix C) and relatively high defect-formation temperatures or long mantle residence times. This is evidenced by several HPHT experiments in which annealing of synthetic Type Ib diamond produces a 3107 cm−1 peak at 1900-2100 °C where peak intensity increases with increasing temperature up to 2650 °C [61,62]. The 3107 cm−1 peak is also observed in CVD diamond during annealing at 2200 °C [63]. Uniaxial stress experiments suggest the defect associated with the 3107 cm−1 peak is trigonal and the C-H bond is oriented parallel to the [111] crystallographic axis [64]. Using the evidence described above, Goss et al. [24] assigned the VN3H defect to the 3107 cm−1 peak family as this is the only trigonal defect that involves N and has a single H atom (a single fundamental C-H stretching mode). The VN3H defect consists of three substitutional N atoms surrounding a vacancy, in which H forms a C-H bond to passivate dangling bonds (uncoupled electrons) of the fourth C atom.

Other than the overtone and combination bands, no other peaks have intensities that correlate with the intensity of the 3107 cm−1 and/or 1405 cm−1 peaks, thus one can assume the associated defect contains one H atom which is related to a single C-H stretching and bending frequency. As shown above, N does not bond to H (or H-bonded C) in this defect. However, the intensity of the 3107 cm−1 peak often shows a positive correlation with N content [42,61] and thus one can also assume N is involved in this defect. Moreover, the absence of the 3107 cm−1 peak in pure Type Ib diamonds suggest involvement of highly aggregated N (e.g. N3-centers, VN3 defects) or B-centers (VN4 defects) as opposed to C-centers (single substitutional N defects), see Appendix C) and relatively high defect-formation temperatures or long mantle residence times. This is evidenced by several HPHT experiments in which annealing of synthetic Type Ib diamond produces a 3107 cm−1 peak at 1900-2100 °C where peak intensity increases with increasing temperature up to 2650 °C [61,62]. The 3107 cm−1 peak is also observed in CVD diamond during annealing at 2200 °C [63]. Uniaxial stress experiments suggest the defect associated with the 3107 cm−1 peak is trigonal and the C-H bond is oriented parallel to the [111] crystallographic axis [64]. Using the evidence described above, Goss et al. [24] assigned the VN3H defect to the 3107 cm−1 peak family as this is the only trigonal defect that involves N and has a single H atom (a single fundamental C-H stretching mode). The VN3H defect consists of three substitutional N atoms surrounding a vacancy, in which H forms a C-H bond to passivate dangling bonds (uncoupled electrons) of the fourth C atom.