Sheridan P J
Gas and Particulate Science Division, National Bureau of Standards, Gaithersburg, Maryland 20899.
J Electron Microsc Tech. 1989 Jan;11(1):41-61. doi: 10.1002/jemt.1060110107.
The relative sensitivity of an analytical electron microscope and energy-dispersive x-ray detector to x-rays of various elements is investigated through an extensive kASi factor study. Elemental standards, primarily National Bureau of Standards multielement research glasses, were dry-ground into submicrometer-sized particles and analyzed at 200 kV accelerating potential. The effect of self-absorption of x-rays by the particle has been corrected for, allowing the experimental kASi factors from this study to approximate those that could be obtained from "infinitely thin" specimens. Whenever possible, elemental k-factors were determined by the analysis of many (up to a maximum of nine) different standard materials. Experimental kASi factors were calculated for a wide range of K alpha, L alpha, and M alpha x-ray lines. For comparison, theoretical kASi factors, employing a variety of ionization cross sections, were computed. Good agreement is obtained between several of the theoretical k-factor models and the experimental results. Mass volatilization of Na and K from the small glass particles during analysis is discussed, as are observations that the grinding and/or dispersing of standard materials in a liquid (such as ethanol) may promote leaching of certain elements from the particle matrix.
通过广泛的kASi因子研究，考察了分析型电子显微镜和能量色散X射线探测器对各种元素X射线的相对灵敏度。元素标准物质，主要是国家标准局的多元素研究玻璃，被干磨成亚微米大小的颗粒，并在200 kV加速电压下进行分析。已对颗粒对X射线的自吸收效应进行了校正，使得本研究中的实验kASi因子接近从“无限薄”样品中获得的因子。只要有可能，就通过分析多种（最多九种）不同的标准物质来确定元素k因子。针对广泛的Kα、Lα和MαX射线谱线计算了实验kASi因子。为作比较，采用多种电离截面计算了理论kASi因子。在几个理论k因子模型与实验结果之间取得了良好的一致性。讨论了分析过程中小玻璃颗粒中Na和K的质量挥发情况，以及标准物质在液体（如乙醇）中的研磨和/或分散可能促进某些元素从颗粒基质中浸出的观察结果。
