Institute of Industrial Science, University of Tokyo, 153-8505, Tokyo, Japan.
ACS Nano. 2013 Jun 25;7(6):5058-63. doi: 10.1021/nn400605z. Epub 2013 May 28.
Various dopants are added in commercially available optical glass fibers. The specific atomic species and charge state of lanthanide dopants are known to significantly influence the fiber's optical properties. For understanding the role of dopants on the optical properties, atomic-scale identification of the lanthanide dopants in the optical fiber is crucial. Aberration-corrected scanning transmission electron microscopy (STEM) is especially powerful for visualizing individual atoms of heavy elements buried in a matrix composed of light elements. Here, we apply aberration-corrected high-angle annular dark field (HAADF)-STEM to directly visualize individual erbium (Er) dopants buried in the optical glass fiber. Molecular dynamics and image simulations are used to interpret the experimental images and draw quantitative conclusions. The visibility of the buried Er atoms in the amorphous glass is strongly dependent on the defocus and specimen thickness, and only Er atoms in very thin regions can be reliably identified.
各种掺杂剂被添加到市售的光学玻璃纤维中。已知镧系掺杂剂的特定原子种类和电荷态会显著影响光纤的光学性质。为了了解掺杂剂对光学性质的影响，在光纤中原子尺度上识别镧系掺杂剂是至关重要的。像差校正扫描透射电子显微镜（STEM）对于观察埋在由轻元素组成的基质中的重元素的单个原子特别有效。在这里，我们应用像差校正高角度环形暗场（HAADF）-STEM 直接观察埋在光纤中的单个铒（Er）掺杂剂。分子动力学和图像模拟用于解释实验图像并得出定量结论。在非晶态玻璃中埋入的 Er 原子的可见度强烈依赖于离焦和样品厚度，只有在非常薄的区域中的 Er 原子才能可靠地识别。
