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Hainschwang, T., Notari, F., Fritsch, E. & Massi, L. (2006) Natural, untreated diamonds showing the A, B and C infrared absorptions ("ABC diamonds"), and the H2 absorption. Diam. Relat. Mat. 15 1555–1564.
Added by: Florent Boucher (2016-05-12 13:21:36) |
| Type de référence: Article DOI: 10.1016/j.diamond.2005.12.029 Numéro d'identification (ISBN etc.): 0925-9635 Clé BibTeX: Hainschwang2006 Voir tous les détails bibliographiques  |
Catégories: PMN Mots-clés: Defect characterization, hpht, Natural diamond, nitrogen Créateurs: Fritsch, Hainschwang, Massi, Notari Collection: Diam. Relat. Mat. |
Consultations : 1/491
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| Résumé |
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Unusual brown to yellow diamonds of mixed type Ib/IaAB were analyzed. The occurrence of nitrogen in a combination of A, B and C centers directly detectable by IR spectroscopy in natural diamonds is considered to be extremely rare. We propose to call such stones ABC diamonds for short. These diamonds are characterized by a color, luminescence, and anomalous double refraction distribution which results from mixed growth: a center core formed by cuboid growth, rich in nitrogen, covered by an outer rim of "normal" octahedral growth, with much less nitrogen. Nitrogen in the core is present in a more aggregated state than in the rim, which is practically pure type Ib. In the infrared spectra, besides A, B and C 1-phonon absorptions a large number of previously undescribed, tentatively H-related features were identified in some samples; these proposed H-related features were only present in the periphery of the core and the rim of the diamonds, in the core practically no hydrogen was detected. The low temperature Vis/NIR spectra were mainly characterized by two defect-induced centers: the H2 center, and the apparently new 905 rim vibronic absorption with phonon-side bands at 880, 867, 847 rim plus a feature at 806.5 nm. The 905 rim absorption can possibly be attributed to a hydrogen-related center. Although these diamonds present a combination of spectroscopic characteristics (A + B + C center absorptions, H2 absorptions) deemed characteristic of certain HPHT-treated type la diamonds, they cannot be confused for such treated diamonds on the basis of their color, color distribution and some spectral peculiarities. (c) 2006 Elsevier B.V. All rights reserved.
Added by: Florent Boucher |