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| Lagerwey, A.A.F.. |
| A selection of well developed apatite crystals of different habit and colour, originating from the tungsten-tin deposits of Panasqueira in Portugal, were analyzed by means of non-destructive optical methods. Phenomena of pleochroism, absorption and luminescence line-spectra, broadband-spectra and phosphorescence were studied. On the basis of extensive and systematic data, obtained from more than sevenhundred polarized spectrophotograms, registered of about seventy apatites from different types of deposit, and of a whole range of fluorapatites, doped with lanthanides and transition elements, it was possible to define the particular type of crystalfield and the nature and quantity of a number of trace elements, present in the fluorapatite from Panasqueira.... |
| Tipo: Article / Letter to the editor |
Palavras-chave: 38.30. |
| Ano: 1977 |
URL: http://www.repository.naturalis.nl/record/317463 |
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| Lagerwey, A.A.F.. |
| A new instrumental method for spectrographical detection of particularities of crystal fields around optically active ions, such as the trivalent chromium ion, was applied to an investigation of red magnesium-spinels from the Ratnapura gem gravels; also from Kangaiyam in India and some other sources for comparison. The method is characterized by analysis of luminescence spectra in the red and near infrared ranges excited by a concentrated flux of blue radiation, and analysed with a spectrograph of considerable optical power. Spectrograms are enregistered on photographic material of high resolving power; they reveal multiplet structures and intensity-distributions of component lines. Slight variations in spectral structure are significant for the detection... |
| Tipo: Article / Letter to the editor |
Palavras-chave: 38.30. |
| Ano: 1974 |
URL: http://www.repository.naturalis.nl/record/317401 |
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