UV-VIS-NIR Absorption Spectroscopy of Natural Pastel and Vivid Colored "Padparadscha" - Sapphires Enhanced by the New E(IM)-Method.
Detection of Unstable Color Centers.
Fig. 30 Polarized UV-VIS-NIR absorption spectra of yellow sapphires produced by the new method E(IM1). The spectra are dominated by iron (Fe3+ and Fe3+ -pairs) for spectrum No. 3. Increase of Fe-concentrations (from 1 to 3) as determined by ED-XRF analyses. Presence of color centers interpreted on the basis of the spectral curve (increasing absorption towards the blue region of the spectrum) and Mg-concentrations (See LA-ICP-MS Data Table 4). Compare also with Lit. 04.
Fig. 31 Polarized UV-VIS-NIR absorption spectra of a diffusion-treated blue sapphire (T ) (See blue line), and blue sapphire produced by enhancement with the new technique E(IM1). Note: Major differences in the absorption characteristics in the UV region of the spectrum. Surface diffusion-treated sapphires (T) show more transparency in the lower UV und blue region of the spectrum between 300 and 450nm.
