Adsorption of carbonate-derived molecules on the surface of carbonate-containing apatites
- 1 January 1991
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions
- Vol. 87 (19) , 3137-3141
- https://doi.org/10.1039/ft9918703137
Abstract
Carbonated apatites synthesized at low temperatures were dried until constant weight at 25 °C. Two 99%13C-enriched samples were examined with EPR after X-irradiation. The observed spectra are interpreted in terms of five paramagnetic radicals, i.e. on O–, two CO– 3 and two CO– 2 radicals. As a result of the 13C hyperfine coupling, practically no signals were found in the region around g= 2, where EPR signals originating from 12C-containing radicals (commonly called 12C signals) are to be expected. Afterwards, the apatite powders were spread out in order to ensure a good contact of the apatite surface with the surrounding atmosphere. The samples were again X-irradiated and re-examined with EPR. Strong 12C signals were detected and attributed to surface radicals. Two different paramagnetic species were tentatively identified as CO– 2 and CO– radicals adsorbed on the apatite surface. The g values for these radicals are g1= 2.0030, g2= 2.0015, g3= 1.9973 for the CO– 2 radical and g1= 2.0058, g2= 2.0041, g3= 2.0023 for the assumed CO– radical.Keywords
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