Novel Robust Internal Calibration Procedure for Precise FT-IR Measurements of Nitrogen Impurities in Diamonds

FT-IR spectroscopy is the basic finger-print method for qualitative and quantitative analysis of nitrogen, boron, and hydrogen impurities in natural and synthetic diamonds. In quantitative measurements of impurity concentrations, external standard samples are required for the calibration procedure during the analysis. In this study, the double-phonon mid-IR absorption coefficient of optical phonons of the diamond host matrix, the robust internal mid-IR absorption standard, was accurately measured for tens of diverse diamond samples, thus enabling precise calibrated measurements of ultra-low detectable impurity concentrations.