X射线荧光光谱分析中谱线重叠校正系数的测量

摘要

应用整套标准样品法和基本参数(FP)法计算谱线重叠校正系数(K)效果较好.应用整套标准样品法需选用与被测样品具有相同基体和近似组成的标准样品;由于共存组分的谱线重叠的干扰常导致校正曲线产生较大的负截距,需通过多次迭代计算消除截距而使曲线通过原点,因为只有这样得到的K和M才是真值.实践中常有一些例子不能用整套标准样品法计算K值,例如钢中测定低含量铬时受到钒的重叠干扰问题.在此实例中除了钒对铬的谱线重叠干扰之外,还有仪器通道材料的干扰,此时,必须先用瑞利散射校正法消除此干扰后,选用铁基的标准样品,用FP法计算K值,可消除钒对铬的谱线重叠干扰.%It was shown that for determination of correction coefficients of spectral overlap (K),the method using sets of standard samples(Ⅰ) and the method of fundamental parameters (FP,Ⅱ) were suitable to be used.In applying method I,standard samples with same matrix and similar components of testing samples should be chosen,and spectral overlap often led to negative intercept in the calibration curve.To obtain true values of K and M,several times of iterative calculations were applied to eliminate the intercept and to make the calibration curve passing through the origin.Instances were encountered where method Ⅰ was not applicable.For examples,determination of values of K for elimination the interference of spectral overlap of Cr by V in determination of low contents of chromium in steels.In this case,besides the interference of overlap by V,interference due to the pathway material of the instrument was happened,and it was necessary to eliminate it first,and the correction by applying Rayleigh scattering was performed.Then the value of K was measured and calculated by the FP method using steel standard samples.The interference of spectral overlap of Cr by V was eliminated.