Hydrogen in natural diamond: Quantification of N3VH defects using SIMS and FTIR data

Abstract

A set of ten diamonds from different sources representing the main types of physical classification (IaA, IaAB, IaB and IIa) has been first explored by FTIR spectroscopy and SIMS calibrated by hydrogen ion implantation. The concentrations of hydrogen in the studied diamonds measured by SIMS range between 9.98 and 47.6 at.ppm or from 1.76 × 10¹⁸ to 8.40 × 10¹⁸ at./cm³. The 3107 cm⁻¹ absorption line has been detected by FTIR spectroscopy (resolution near 1 cm⁻¹) in five studied diamonds (IaB and IaAB). The 3107 cm⁻¹ IR absorption lines due to H defects in these diamonds have been successfully described by the Lorentzian shape and their parameters have been evaluated. Based on the linear regression equation relating intensities of the 3107 cm⁻¹ IR absorption lines in the studied diamonds with their H defect concentrations, the H defect IR absorption at 3107 cm⁻¹ in diamond has been quantified. The absorption calibration constant for diamond's 3107 cm⁻¹ absorption line is 386 ± 64 ppb cm². The corresponding cross-section per one H defect σ₃₁₀₇ (cm²) = (9.34 ± 1.25) × 10⁻¹⁸ /Γ (cm⁻¹), Γ is the full width at half maximum (FWHM) of the 3107 cm⁻¹ absorption line. Based on a widely accepted interpretation that the H defect resulting in the 3107 cm⁻¹ IR absorption peak in diamonds is the N₃VH defect, the values of the obtained calibration constant and cross-section have been assigned to the N₃VH defect in diamond. The equations relating concentration of the N₃VH defect ([N₃VH]) with the 3107 cm⁻¹ IR absorption line integrated intensity (I₃₁₀₇) and intensity (α₃₁₀₇) are as follows: [N₃VH] (ppb) = (386 ± 64) I₃₁₀₇; [N₃VH] (ppm) = (0.607 ± 0.080) α ₃₁₀₇ (cm⁻¹)Γ (cm⁻¹). Hydrogen impurities that do not contribute to the IR absorption at the 3107 cm⁻¹ peak were detected in all studied diamonds.