NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
ACS Nano. 2013 Feb 26;7(2):921-31. doi: 10.1021/nn303600e. Epub 2013 Jan 15.
Here it is demonstrated that multiple-energy, anomalous small-angle X-ray scattering (ASAXS) provides significant enhancement in sensitivity to internal material boundaries of layered nanoparticles compared with the traditional modeling of a single scattering energy, even for cases in which high scattering contrast naturally exists. Specifically, the material-specific structure of monodispersed Fe₃O₄|γ-Mn₂O₃ core|shell nanoparticles is determined, and the contribution of each component to the total scattering profile is identified with unprecedented clarity. We show that Fe₃O₄|γ-Mn₂O₃ core|shell nanoparticles with a diameter of 8.2 ± 0.2 nm consist of a core with a composition near Fe₃O₄ surrounded by a (Mn(x)Fe(1-x))₃O₄ shell with a graded composition, ranging from x ≈ 0.40 at the inner shell toward x ≈ 0.46 at the surface. Evaluation of the scattering contribution arising from the interference between material-specific layers additionally reveals the presence of Fe₃O₄ cores without a coating shell. Finally, it is found that the material-specific scattering profile shapes and chemical compositions extracted by this method are independent of the original input chemical compositions used in the analysis, revealing multiple-energy ASAXS as a powerful tool for determining internal nanostructured morphology even if the exact composition of the individual layers is not known a priori.
本文证明，与传统的单一散射能建模相比，多能量异常小角 X 射线散射（ASAXS）可显著提高对层状纳米粒子内部材料边界的灵敏度，即使在存在高散射对比度的情况下也是如此。具体来说，确定了单分散 Fe₃O₄|γ-Mn₂O₃核|壳纳米粒子的材料特定结构，并以前所未有的清晰度确定了每个组件对总散射轮廓的贡献。我们表明，直径为 8.2 ± 0.2nm 的 Fe₃O₄|γ-Mn₂O₃核|壳纳米粒子由组成接近 Fe₃O₄的核组成，周围是组成逐渐变化的（Mn(x)Fe(1-x))₃O₄壳，从内壳的 x ≈ 0.40 到表面的 x ≈ 0.46。对源于材料特定层之间干涉的散射贡献的评估还揭示了存在没有涂层壳的 Fe₃O₄核。最后，发现通过这种方法提取的特定材料散射轮廓形状和化学成分独立于分析中使用的原始输入化学成分，即使个别层的精确组成事先未知，多能量 ASAXS 也是确定内部纳米结构形态的有力工具。
