THE RELATIONSHIP BETWEEN INFRARED-ABSORPTION AND THE A DEFECT CONCENTRATION IN DIAMOND

The nitrogen concentrations of a suite of thirteen purely type IaA dia monds have been determined by a destructive method involving combustio n of the specimens and measurement, by capacitance manometry, of the r eleased nitrogen. These values have been related to measurements of th e infrared absorption strength due to nitrogen in the form of A centre s, or nitrogen-pair defects, in the specimens. It is found that an abs orption coefficient of 1 cm-1, at 1282 wavenumbers, is produced by 16. 1 +/- 1 at. p.p.m. of nitrogen in this form. This is in good agreement with the values found by inert-gas fusion and by an indirect method d escribed in the previous paper. Application of a statistical analysis to these three consistent sets of results taken collectively suggests that a reliable working value for the absorption strength at 1282 wave numbers due to the A defect in diamond would be 1 cm-1 per 16.5 +/- 1 at. p.p.m.