| Popis: |
A set of natural diamonds, representing the main types of physical classification (IaA, IaAB, IaB and IIa), was studied with the utilisation of FTIR and SIMS with the implantation of hydrogen into a standard sample. The volumetric concentrations of hydrogen in the studied diamonds are between 5-24 at.ppm. According to their FTIR spectra, the diamonds form two groups: low-hydrogen (0.07‒1.33 cm-1 arbitrary units) and hydrogen-rich (8.4‒15.2 cm-1 arbitrary units) diamonds. The volumetric concentrations of hydrogen, established with the use of SIMS correspond to the FTIR data: low-hydrogen diamonds have 5‒11 at.ppm of hydrogen, and hydrogen-rich diamonds have 13-24 at.ppm of hydrogen. There is a correlation between SIMS and FTIR determinations of hydrogen concentrations in diamonds. Each group is characterised by its trend. The correlation between volumetric hydrogen concentration and FTIR characteristics for low-hydrogen diamonds is expressed by the equations: [H]at.ppm = 10.71*[H]IR + 3.79 and for high-hydrogen diamonds and [H]at.ppm = 1.57*[H]IR-0.3. Our observations confirm bonding hydrogen with nitrogen in H-rich diamonds. Another structure may be suggested for the hydrogen impurity in low-H diamonds. It is also possible that the instrumentally determined hydrogen concentrations in diamond reflect IR-active and other hydrogen centres. |
