Laboratorium für Elektronenmikroskopie, Universität Karlsruhe (TH), D-76128 Karlsruhe, Germany.
Microsc Microanal. 2009 Dec;15(6):505-23. doi: 10.1017/S143192760999105X. Epub 2009 Oct 27.
A comprehensive electron energy-loss spectroscopy study of niobium (Nb) and stable Nb-oxide phases (NbO, NbO2, Nb2O5) was carried out. In this work (Part I), the plasmons and energy-loss near-edge structures (ELNES) of all relevant Nb edges (Nb-N2,3, Nb-M4,5, Nb-M2,3, Nb-M1, and Nb-L2,3) up to energy losses of about 2600 eV and the O-K edge are analyzed with respect to achieving characteristic fingerprints of Nb in different formal oxidation states (0 for metallic Nb, +2 for NbO, +4 for NbO2, and +5 for Nb2O5). Chemical shifts of the Nb-N2,3, Nb-M4,5, Nb-M2,3, and Nb-L2,3 edges are extracted from the spectra that amount to about 4 eV as the oxidation state increases from 0 for Nb to +5 for Nb2O5. Four different microscopes, including a 200 keV ZEISS Libra with monochromator, were used. The corresponding wide range of experimental parameters with respect to the primary electron energy, convergence, and collection semi-angles as well as energy resolution allows an assessment of the influence of the experimental setup on the ELNES of the different edges. Finally, the intensity of the Nb-L2,3 white-line edges is correlated with niobium 4d-state occupancy in the different reference materials.
进行了一项全面的电子能量损失光谱研究，研究对象是铌（Nb）和稳定的 Nb 氧化物相（NbO、NbO2、Nb2O5）。在这项工作中（第一部分），分析了所有相关 Nb 边缘（Nb-N2,3、Nb-M4,5、Nb-M2,3、Nb-M1 和 Nb-L2,3）的等离子体和能量损失近边结构（ELNES），能量损失高达约 2600 eV，以及 O-K 边缘，以获得不同形式氧化态（金属态 Nb 的 0 价、NbO 的+2 价、NbO2 的+4 价和 Nb2O5 的+5 价）下 Nb 的特征指纹。从光谱中提取出 Nb-N2,3、Nb-M4,5、Nb-M2,3 和 Nb-L2,3 边缘的化学位移，随着氧化态从 0 价 Nb 增加到+5 价 Nb2O5，化学位移约为 4 eV。使用了包括配备单色仪的 200 keV ZEISS Libra 在内的四台不同的显微镜。相应的实验参数范围很广，包括初级电子能量、收敛角和收集半角以及能量分辨率，这允许评估实验设置对不同边缘的 ELNES 的影响。最后，将 Nb-L2,3 白线边缘的强度与不同参考材料中铌 4d 态占据数相关联。
