X射线荧光光谱中影响理论计算相对强度的主要因素

提高理论相对强度计算准确度对X射线荧光定量分析及基体效应的数学校正至关重要。本文对X射线荧光光谱中影响理论计算相对强度的几种主要因素进行了探讨。考察了谱仪几何因子的不准确性对理论相对强度的影响,用三种不同来源的X光管原级谱强度分布计算和比较了一系列谱线的相对强度,通过详细考察发现不同作者发表的质量吸收系数之间及其与实测值之间在三个区域存在显著差异,并比较了用四种常用质量吸收系数算法计算的一系列谱线的相对强度,根据不同作者的激发因子算法编制了相应的计算机程序,对K~α,L~α和M~α的激发因子考察了它们之间的差异。

Influences of key factors on theoretically calculated relative intensities in X-ray fluorescence spectrometry

It is very important in the quantitative X- ray fluorescence (XRF) analysis and the mathematical correction for interelement effects to increase the accuracy of the theoretically calculated relative intensities (Ri). In this paper, the influences of several key factors on Ri were investigated. Effect of arbitrary change of the spectrometer geometry on Ri was studied. A comparison was made when using three different X - ray tube primary spectral distribution sources to calculate Ri of some analytical lines. It was observed that there were notable differences within the four commonly used compilations of mass absorption coefficients (MAC) or between calculated and experimental MAC values when the energy of the incident X - ray lines fell in the regions of LII - LIII or MIV - MV absorption edges of an absorber. A series of Ri were calculated based on a set of simulated fused samples and compared when using the four MAC compilations. The results showed MAC selection was more important for improving the accuracy of the calculated relative intensities. The comparison of the four different compilations of the excitation factors indicated that the average relative differences were 2.6% for Ka ,40.7% for La1 and 131.9% for Ma1.