In the spectral range of local vibrations of high energy (2700 to 3200 cm") many sharp lines of low intensity were found (Fig. 3a).They all are believed to belong to hydrogen-related defects [3,10—12].
These lines were also reported in spectra of CVD diamonds [8]. The 3123 cm“ line, which is due to NVHO defect [13,14], is a common absorption feature of CVD diamonds both in as-grown state and after
HPHT treatment. The NVHO defect was detected in LPHT-annealed CVD diamonds too [15]. The well-known 3107 cm” line is due to N3V-H defect [11]. The presence of the 3107 cm” center in spectra of
as-received diamonds is indicative of nitrogen aggregation in them and thus confirms the application of HPHT treatment to these diamonds.