Variations in the absorption of infra-red radiation by diamond

Abstract

Using a Residual-ray apparatus, the infra-red absorption coefficients have been measured for 37 cleavage plates of diamond in the 8 µ region. While the absorption coefficients measured with an infra-red monochromator in the region 4–5 µ remain constant within the error of the measurement for all diamonds, those in the 8 µ region show a wide range of variation. The results are correlated with the behaviour of diamond in respect of luminescence and ultraviolet absorption. Some cleavage plates of diamond have also been shown to exhibit patterns of infra-red transparency in the 8 µ region, closely analogous to the patterns of ultraviolet transparency and of luminescence.