簿膜X射线能谱定量分析准确度的探讨

An Investigation of Quanfifative Energy-Dispersive x-ray Analysis of Thin Foils

  • 摘要: 本文通过在EM400T透射电镜上用一些标准成分的样品进行薄膜无标样成份分析实验,检验了EDAX9100能谱仪的分析准确度。在本试验所用的样品范围内,其准确度为:近邻元素同一X光线系分析相对误差为5~10%,非近邻元素不同线系分析相时误差较大,可达20~50%。试验证明在分析元素的质量吸收系数之差Δμ较大时,还必须考虑吸收修正。通过对K因子的讨论,得出与本实验结果符合比较好的薄膜能谱理论公式组合为:取BeThe-Powell公式的电离截面QBP∞(1n0.65U)/U·Ej2,K系、L系、M系的线系常数调整后取bK:bL:bM=0.35:0.35:0.24,荧光产额用Bambynek的ωK和wentzel的ωL和ωM。用以上公式组合并经过吸收修正,对所有线系计算结果相对误差小于10%。

     

    Abstract: The accuracy of quantitative analysis of thin foils in The energy dispersive x-ray spectrometer, EDAX9100, has been measured with samples of known composition.The results indicate that at 100KV, a relative error of 5-10% Can be achived using The EDAX9100 program when K-K or L-L x-ray Lines of elements with close atomic number are being analyzed. The relative error becomes progressively worse,up to abont 20% to 50% if The difference in atomic number between The two analyzed elements increaces, and the different x-ray lines are analgzed.
    The absorption of thin film specimens has been studied The results indicate that x-ray absorption within the sample must be Considered when there is a significant difference in The energy of The Characteristic x-raysAt lower voltages a correction must be applied to the K factor in the EDAX9100 program. The EDAX9100 program must be Corrected for using iines from different x-rag shells.Reasonable equations for calculating the lonization cross section and fluorescence yields have been Chosen, and the ratio of coefficients of K, L and M shell lines have been calculated to be qK:bL:bM=0.35:0.35:0.24.
    The relative error after correcting the program for absorption,voltage,and different x-ray shells, is less than 10% for all x-ray lines analyged.

     

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