Department of Materials Engineering, McGill University, M.H. Wong Building, 3610 University Street, Montréal, Québec H3A 2B2, Canada.
Microsc Microanal. 2012 Oct;18(5):915-40. doi: 10.1017/S1431927612001468.
This article reviews different methods used to perform quantitative X-ray microanalysis in the electron microscope and also demonstrates the urgency of measuring the fundamental parameters of X-ray generation for the development of accurate standardless quantitative methods. Using ratios of characteristic lines acquired on the same X-ray spectrum, it is shown that the Cliff and Lorimer K A-B factor can be used in a general correction method that is appropriate for all types of specimens and electron microscopes, providing that appropriate corrections are made for X-ray absorption, fluorescence, and indirect generation. Since the fundamental parameters appear in the K A-B factor, only the ratio of the ionization cross sections needs to be known, not their absolute values. In this regard, the measurement of ratios of the K A-B factor (or intensities at different beam energies of the same material with no change of beam spreading in the material) permits the validation for the best models to compute the ratio of ionization cross sections. It is shown, using this method, that the nonrelativistic Bethe equation, to compute ionization cross section, is very close to the equation of E. Casnati et al. (J Phys B 15, 155-167, 1982) and also to the equations proposed by D. Bote and F. Salvat (Phys Rev A 77, 042701, 2008) for the computation of the ratio of ionization cross sections. The method is extended to show that it could be used to determine the values of the Coster-Kronig transitions factors, an important fundamental parameter for the generation of L and M lines that is mostly known with poor accuracy. The detector efficiency can be measured with specimens where their intensities were measured with an energy dispersive spectrometer detector, the efficiency of which has been measured in an X-ray synchrotron (M. Alvisi et al., Microsc Microanal 12, 406-415, 2006). The spatial resolution should always be computed when performing quantitative X-ray microanalysis and the equations of R. Gauvin (Microsc Microanal 13(5), 354-357, 2007) for bulk materials and the one presented in this article for thin films should be used. The effects of X-rays generated by fast secondary electrons and by Auger electrons are reviewed, and their effect can be detrimental for the spatial resolution of materials involving low-energy X-ray lines, in certain specific conditions. Finally, quantitative X-ray microanalysis of heterogeneous materials is briefly reviewed.
本文回顾了在电子显微镜中进行定量 X 射线微分析的不同方法，并论证了测量 X 射线产生基本参数的紧迫性，以便开发准确的无标定量方法。通过在同一条 X 射线光谱上获得的特征线的比值，可以证明 Cliff 和 Lorimer K A-B 因子可以用于一般的校正方法，适用于所有类型的样品和电子显微镜，只要对 X 射线吸收、荧光和间接产生进行适当的校正。由于基本参数出现在 K A-B 因子中，因此只需要知道电离截面的比值，而不需要知道其绝对值。在这方面，通过测量 K A-B 因子的比值（或相同材料在不同束能下的强度，而材料中的束展宽没有变化），可以验证用于计算电离截面比值的最佳模型。本文使用这种方法表明，非相对论 Bethe 方程用于计算电离截面非常接近 E. Casnati 等人的方程（J Phys B 15, 155-167, 1982），也接近 D. Bote 和 F. Salvat 提出的方程（Phys Rev A 77, 042701, 2008），用于计算电离截面的比值。该方法可扩展到表明，它可用于确定 Coster-Kronig 跃迁因子的值，这是 L 和 M 线产生的一个重要基本参数，其精度通常很差。探测器效率可以通过用能量色散谱仪探测器测量其强度的样品来测量，该探测器的效率已经在 X 射线同步加速器中进行了测量（M. Alvisi 等人，Microsc Microanal 12, 406-415, 2006）。在进行定量 X 射线微分析时，应始终计算空间分辨率，并且应使用 R. Gauvin（Microsc Microanal 13(5), 354-357, 2007）为体材料和本文提出的用于薄膜的公式。本文回顾了由快速二次电子和俄歇电子产生的 X 射线的影响，并论证了在某些特定条件下，这些射线会对涉及低能 X 射线线的材料的空间分辨率产生不利影响。最后，简要回顾了异质材料的定量 X 射线微分析。
