Photoluminescence Spectra of Chrysoberyls from Various Origins
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摘要:
光致发光光谱因其无损、高灵敏度和高分辨率的特性，被广泛应用于宝石学和矿物学领域。采用无损激光激发光致发光光谱、激光烧蚀电感耦合等离子体质谱等技术手段对缅甸、巴西、斯里兰卡、坦桑尼亚等几个宝石产地的金绿宝石样品及其合成品进行了研究。结果表明，所有金绿宝石样品的光致发光光谱非常相似，它们主要是Cr离子发射，光谱均显示有两条狭窄的R线，可以帮助判断样品是天然或合成，也可以提供关于天然样品的地质来源的信息。在收集的光致发光光谱中，这些R线的峰值位置在很小的波长范围内变化，这些变化的来源依赖性可能有助于识别未知样本的地理来源。其中，合成金绿宝石样品的R2线位于最长的波长，天然金绿宝石样品则在更短的波长。通过R线峰位和相应的元素浓度的比较，R线的峰值位移与Al2O3浓度的增加有较强的相关性，这表明微量元素取代铝位点可能是导致R线峰位偏移的原因。
Abstract:Photoluminescence spectroscopy is widely applied in the fields of gemmology and mineralogy utilizing its non-destructive, high-sensitivity, and high-resolution features. Chrysoberyls from gem-mining regions such as Myanmar, Brazil, Sri Lanka, Tanzania and synthetic chrysoberyl samples were studied by non-destructive laser-induced photoluminescence spectroscopy and laser ablation-inductively coupled plasma-mass spectrometry. The experimental results demonstrate a high degree of similarity in the comparative photoluminescence spectra across all examined samples, manifested by the presence of two narrow R-lines that are predominantly attributed to the emissive properties of Cr ion. This characteristic signature not only facilitates the discrimination between natural and synthetic chrysoberyl samples but also provide information about natural samples' geological origin. In the collected spectra, peak positions of these R-lines varies across a small range of wavelengths; the origin-dependent nature of these variations may be helpful in identifying the geographic source of unknown samples. In particular, the R2 line of synthetic chrysoberyl is positioned at the longest wavelength, while for natural chrysoberyl this line is found at the shorter wavelength. Comparisons between R-line peak wavelengths and corresponding element concentrations of samples revealed strong correlations between peak shifts of the R-lines and increases in alumina concentrations. These correlations suggest that the substitution of trace elements for aluminum crystal sites responsible for the R-lines peak shifts.
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Keywords:
- chrysoberyl /
- photoluminescence spectra /
- origin
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